diff --git a/scripts/processDiagnosticMessages.ts b/scripts/processDiagnosticMessages.ts
index 4bdf3ca0178..7577707340a 100644
--- a/scripts/processDiagnosticMessages.ts
+++ b/scripts/processDiagnosticMessages.ts
@@ -6,6 +6,7 @@ interface DiagnosticDetails {
     code: number;
     reportsUnnecessary?: {};
     isEarly?: boolean;
+    elidedInCompatabilityPyramid?: boolean;
 }
 
 type InputDiagnosticMessageTable = Map<string, DiagnosticDetails>;
@@ -63,14 +64,15 @@ function buildInfoFileOutput(messageTable: InputDiagnosticMessageTable, inputFil
         "// generated from '" + inputFilePathRel + "' by '" + thisFilePathRel.replace(/\\/g, "/") + "'\r\n" +
         "/* @internal */\r\n" +
         "namespace ts {\r\n" +
-        "    function diag(code: number, category: DiagnosticCategory, key: string, message: string, reportsUnnecessary?: {}): DiagnosticMessage {\r\n" +
-        "        return { code, category, key, message, reportsUnnecessary };\r\n" +
+        "    function diag(code: number, category: DiagnosticCategory, key: string, message: string, reportsUnnecessary?: {}, elidedInCompatabilityPyramid?: boolean): DiagnosticMessage {\r\n" +
+        "        return { code, category, key, message, reportsUnnecessary, elidedInCompatabilityPyramid };\r\n" +
         "    }\r\n" +
         "    export const Diagnostics = {\r\n";
-    messageTable.forEach(({ code, category, reportsUnnecessary }, name) => {
+    messageTable.forEach(({ code, category, reportsUnnecessary, elidedInCompatabilityPyramid }, name) => {
         const propName = convertPropertyName(name);
         const argReportsUnnecessary = reportsUnnecessary ? `, /*reportsUnnecessary*/ ${reportsUnnecessary}` : "";
-        result += `        ${propName}: diag(${code}, DiagnosticCategory.${category}, "${createKey(propName, code)}", ${JSON.stringify(name)}${argReportsUnnecessary}),\r\n`;
+        const argElidedInCompatabilityPyramid = elidedInCompatabilityPyramid ? `${!reportsUnnecessary ? ", /*reportsUnnecessary*/ undefined" : ""}, /*elidedInCompatabilityPyramid*/ ${elidedInCompatabilityPyramid}` : "";
+        result += `        ${propName}: diag(${code}, DiagnosticCategory.${category}, "${createKey(propName, code)}", ${JSON.stringify(name)}${argReportsUnnecessary}${argElidedInCompatabilityPyramid}),\r\n`;
     });
 
     result += "    };\r\n}";
diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index e29f46f2dec..de5c3b5b358 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -12329,7 +12329,7 @@ namespace ts {
             target: Signature,
             ignoreReturnTypes: boolean): boolean {
             return compareSignaturesRelated(source, target, CallbackCheck.None, ignoreReturnTypes, /*reportErrors*/ false,
-                /*errorReporter*/ undefined, compareTypesAssignable) !== Ternary.False;
+                /*errorReporter*/ undefined, /*errorReporter*/ undefined, compareTypesAssignable) !== Ternary.False;
         }
 
         type ErrorReporter = (message: DiagnosticMessage, arg0?: string, arg1?: string) => void;
@@ -12352,6 +12352,7 @@ namespace ts {
             ignoreReturnTypes: boolean,
             reportErrors: boolean,
             errorReporter: ErrorReporter | undefined,
+            incompatibleErrorReporter: ((source: Type, target: Type) => void) | undefined,
             compareTypes: TypeComparer): Ternary {
             // TODO (drosen): De-duplicate code between related functions.
             if (source === target) {
@@ -12422,7 +12423,7 @@ namespace ts {
                     (getFalsyFlags(sourceType) & TypeFlags.Nullable) === (getFalsyFlags(targetType) & TypeFlags.Nullable);
                 const related = callbacks ?
                     // TODO: GH#18217 It will work if they're both `undefined`, but not if only one is
-                    compareSignaturesRelated(targetSig!, sourceSig!, strictVariance ? CallbackCheck.Strict : CallbackCheck.Bivariant, /*ignoreReturnTypes*/ false, reportErrors, errorReporter, compareTypes) :
+                    compareSignaturesRelated(targetSig!, sourceSig!, strictVariance ? CallbackCheck.Strict : CallbackCheck.Bivariant, /*ignoreReturnTypes*/ false, reportErrors, errorReporter, incompatibleErrorReporter, compareTypes) :
                     !callbackCheck && !strictVariance && compareTypes(sourceType, targetType, /*reportErrors*/ false) || compareTypes(targetType, sourceType, reportErrors);
                 if (!related) {
                     if (reportErrors) {
@@ -12468,6 +12469,9 @@ namespace ts {
                     // wouldn't be co-variant for T without this rule.
                     result &= callbackCheck === CallbackCheck.Bivariant && compareTypes(targetReturnType, sourceReturnType, /*reportErrors*/ false) ||
                         compareTypes(sourceReturnType, targetReturnType, reportErrors);
+                    if (!result && reportErrors && incompatibleErrorReporter) {
+                        incompatibleErrorReporter(sourceReturnType, targetReturnType);
+                    }
                 }
 
             }
@@ -12677,11 +12681,16 @@ namespace ts {
             let depth = 0;
             let expandingFlags = ExpandingFlags.None;
             let overflow = false;
-            let overrideNextErrorInfo: DiagnosticMessageChain | undefined;
+            let overrideNextErrorInfo = 0; // How many `reportRelationError` calls should be skipped in the elaboration pyramid
+            let lastSkippedInfo: [Type, Type] | undefined;
+            let incompatibleStack: [DiagnosticMessage, (string | number)?, (string | number)?, (string | number)?, (string | number)?][] = [];
 
             Debug.assert(relation !== identityRelation || !errorNode, "no error reporting in identity checking");
 
             const result = isRelatedTo(source, target, /*reportErrors*/ !!errorNode, headMessage);
+            if (incompatibleStack.length) {
+                reportIncompatibleStack();
+            }
             if (overflow) {
                 const diag = error(errorNode, Diagnostics.Excessive_stack_depth_comparing_types_0_and_1, typeToString(source), typeToString(target));
                 if (errorOutputContainer) {
@@ -12726,8 +12735,134 @@ namespace ts {
             }
             return result !== Ternary.False;
 
+            function resetErrorInfo(saved: ReturnType<typeof captureErrorCalculationState>) {
+                errorInfo = saved.errorInfo;
+                lastSkippedInfo = saved.lastSkippedInfo;
+                incompatibleStack = saved.incompatibleStack;
+                overrideNextErrorInfo = saved.overrideNextErrorInfo;
+                relatedInfo = saved.relatedInfo;
+            }
+
+            function captureErrorCalculationState() {
+                return {
+                    errorInfo,
+                    lastSkippedInfo,
+                    incompatibleStack: incompatibleStack.slice(),
+                    overrideNextErrorInfo,
+                    relatedInfo: !relatedInfo ? undefined : relatedInfo.slice() as ([DiagnosticRelatedInformation, ...DiagnosticRelatedInformation[]] | undefined)
+                };
+            }
+
+            function reportIncompatibleError(message: DiagnosticMessage, arg0?: string | number, arg1?: string | number, arg2?: string | number, arg3?: string | number) {
+                overrideNextErrorInfo++; // Suppress the next relation error
+                lastSkippedInfo = undefined; // Reset skipped info cache
+                incompatibleStack.push([message, arg0, arg1, arg2, arg3]);
+            }
+
+            function reportIncompatibleStack() {
+                const stack = incompatibleStack;
+                incompatibleStack = [];
+                const info = lastSkippedInfo;
+                lastSkippedInfo = undefined;
+                if (stack.length === 1) {
+                    reportError(...stack[0]);
+                    if (info) {
+                        // Actually do the last relation error
+                        reportRelationError(/*headMessage*/ undefined, ...info);
+                    }
+                    return;
+                }
+                // The first error will be the innermost, while the last will be the outermost - so by popping off the end,
+                // we can build from left to right
+                let path = "";
+                const secondaryRootErrors: typeof incompatibleStack = [];
+                while (stack.length) {
+                    const [msg, ...args] = stack.pop()!;
+                    switch (msg.code) {
+                        case Diagnostics.Types_of_property_0_are_incompatible.code: {
+                            // Parenthesize a `new` if there is one
+                            if (path.indexOf("new ") === 0) {
+                                path = `(${path})`;
+                            }
+                            const str = "" + args[0];
+                            // If leading, just print back the arg (irrespective of if it's a valid identifier)
+                            if (path.length === 0) {
+                                path = `${str}`;
+                            }
+                            // Otherwise write a dotted name if possible
+                            else if (isIdentifierText(str, compilerOptions.target)) {
+                                path = `${path}.${str}`;
+                            }
+                            // Failing that, check if the name is already a computed name
+                            else if (str[0] === "[" && str[str.length - 1] === "]") {
+                                path = `${path}${str}`;
+                            }
+                            // And finally write out a computed name as a last resort
+                            else {
+                                path = `${path}[${str}]`;
+                            }
+                            break;
+                        }
+                        case Diagnostics.Call_signature_return_types_0_and_1_are_incompatible.code:
+                        case Diagnostics.Construct_signature_return_types_0_and_1_are_incompatible.code:
+                        case Diagnostics.Call_signatures_with_no_arguments_have_incompatible_return_types_0_and_1.code:
+                        case Diagnostics.Construct_signatures_with_no_arguments_have_incompatible_return_types_0_and_1.code: {
+                            if (path.length === 0) {
+                                // Don't flatten signature compatability errors at the start of a chain - instead prefer
+                                // to unify (the with no arguments bit is excessive for printback) and print them back
+                                let mappedMsg = msg;
+                                if (msg.code === Diagnostics.Call_signatures_with_no_arguments_have_incompatible_return_types_0_and_1.code) {
+                                    mappedMsg = Diagnostics.Call_signature_return_types_0_and_1_are_incompatible;
+                                }
+                                else if (msg.code === Diagnostics.Construct_signatures_with_no_arguments_have_incompatible_return_types_0_and_1.code) {
+                                    mappedMsg = Diagnostics.Construct_signature_return_types_0_and_1_are_incompatible;
+                                }
+                                secondaryRootErrors.unshift([mappedMsg, args[0], args[1]]);
+                            }
+                            else {
+                                const prefix = (msg.code === Diagnostics.Construct_signature_return_types_0_and_1_are_incompatible.code ||
+                                    msg.code === Diagnostics.Construct_signatures_with_no_arguments_have_incompatible_return_types_0_and_1.code)
+                                        ? "new "
+                                        : "";
+                                const params = (msg.code === Diagnostics.Call_signatures_with_no_arguments_have_incompatible_return_types_0_and_1.code ||
+                                    msg.code === Diagnostics.Construct_signatures_with_no_arguments_have_incompatible_return_types_0_and_1.code)
+                                        ? ""
+                                        : "...";
+                                path = `${prefix}${path}(${params})`;
+                            }
+                            break;
+                        }
+                        default:
+                            return Debug.fail(`Unhandled Diagnostic: ${msg.code}`);
+                    }
+                }
+                if (path) {
+                    reportError(path[path.length - 1] === ")"
+                        ? Diagnostics.The_types_returned_by_0_are_incompatible_between_these_types
+                        : Diagnostics.The_types_of_0_are_incompatible_between_these_types,
+                        path
+                    );
+                }
+                else {
+                    // Remove the innermost secondary error as it will duplicate the error already reported by `reportRelationError` on entry
+                    secondaryRootErrors.shift();
+                }
+                for (const [msg, ...args] of secondaryRootErrors) {
+                    const originalValue = msg.elidedInCompatabilityPyramid;
+                    msg.elidedInCompatabilityPyramid = false; // Teporarily override elision to ensure error is reported
+                    reportError(msg, ...args);
+                    msg.elidedInCompatabilityPyramid = originalValue;
+                }
+                if (info) {
+                    // Actually do the last relation error
+                    reportRelationError(/*headMessage*/ undefined, ...info);
+                }
+            }
+
             function reportError(message: DiagnosticMessage, arg0?: string | number, arg1?: string | number, arg2?: string | number, arg3?: string | number): void {
                 Debug.assert(!!errorNode);
+                if (incompatibleStack.length) reportIncompatibleStack();
+                if (message.elidedInCompatabilityPyramid) return;
                 errorInfo = chainDiagnosticMessages(errorInfo, message, arg0, arg1, arg2, arg3);
             }
 
@@ -12742,6 +12877,7 @@ namespace ts {
             }
 
             function reportRelationError(message: DiagnosticMessage | undefined, source: Type, target: Type) {
+                if (incompatibleStack.length) reportIncompatibleStack();
                 const [sourceType, targetType] = getTypeNamesForErrorDisplay(source, target);
 
                 if (target.flags & TypeFlags.TypeParameter && target.immediateBaseConstraint !== undefined && isTypeAssignableTo(source, target.immediateBaseConstraint)) {
@@ -12899,7 +13035,7 @@ namespace ts {
                 }
 
                 let result = Ternary.False;
-                const saveErrorInfo = errorInfo;
+                const saveErrorInfo = captureErrorCalculationState();
                 let isIntersectionConstituent = !!isApparentIntersectionConstituent;
 
                 // Note that these checks are specifically ordered to produce correct results. In particular,
@@ -12949,7 +13085,7 @@ namespace ts {
                     }
                     if (!result && (source.flags & TypeFlags.StructuredOrInstantiable || target.flags & TypeFlags.StructuredOrInstantiable)) {
                         if (result = recursiveTypeRelatedTo(source, target, reportErrors, isIntersectionConstituent)) {
-                            errorInfo = saveErrorInfo;
+                            resetErrorInfo(saveErrorInfo);
                         }
                     }
                 }
@@ -12966,19 +13102,21 @@ namespace ts {
                     const constraint = getUnionConstraintOfIntersection(<IntersectionType>source, !!(target.flags & TypeFlags.Union));
                     if (constraint) {
                         if (result = isRelatedTo(constraint, target, reportErrors, /*headMessage*/ undefined, isIntersectionConstituent)) {
-                            errorInfo = saveErrorInfo;
+                            resetErrorInfo(saveErrorInfo);
                         }
                     }
                 }
 
                 if (!result && reportErrors) {
-                    let maybeSuppress = overrideNextErrorInfo;
-                    overrideNextErrorInfo = undefined;
+                    let maybeSuppress = overrideNextErrorInfo > 0;
+                    if (maybeSuppress) {
+                        overrideNextErrorInfo--;
+                    }
                     if (source.flags & TypeFlags.Object && target.flags & TypeFlags.Object) {
                         const currentError = errorInfo;
                         tryElaborateArrayLikeErrors(source, target, reportErrors);
                         if (errorInfo !== currentError) {
-                            maybeSuppress = errorInfo;
+                            maybeSuppress = !!errorInfo;
                         }
                     }
                     if (source.flags & TypeFlags.Object && target.flags & TypeFlags.Primitive) {
@@ -12998,6 +13136,7 @@ namespace ts {
                         }
                     }
                     if (!headMessage && maybeSuppress) {
+                        lastSkippedInfo = [source, target];
                         // Used by, eg, missing property checking to replace the top-level message with a more informative one
                         return result;
                     }
@@ -13439,7 +13578,7 @@ namespace ts {
                 let result: Ternary;
                 let originalErrorInfo: DiagnosticMessageChain | undefined;
                 let varianceCheckFailed = false;
-                const saveErrorInfo = errorInfo;
+                const saveErrorInfo = captureErrorCalculationState();
 
                 // We limit alias variance probing to only object and conditional types since their alias behavior
                 // is more predictable than other, interned types, which may or may not have an alias depending on
@@ -13531,7 +13670,7 @@ namespace ts {
                                 }
                             }
                             originalErrorInfo = errorInfo;
-                            errorInfo = saveErrorInfo;
+                            resetErrorInfo(saveErrorInfo);
                         }
                     }
                 }
@@ -13543,7 +13682,7 @@ namespace ts {
                             result &= isRelatedTo((<IndexedAccessType>source).indexType, (<IndexedAccessType>target).indexType, reportErrors);
                         }
                         if (result) {
-                            errorInfo = saveErrorInfo;
+                            resetErrorInfo(saveErrorInfo);
                             return result;
                         }
                     }
@@ -13552,25 +13691,25 @@ namespace ts {
                         if (!constraint || (source.flags & TypeFlags.TypeParameter && constraint.flags & TypeFlags.Any)) {
                             // A type variable with no constraint is not related to the non-primitive object type.
                             if (result = isRelatedTo(emptyObjectType, extractTypesOfKind(target, ~TypeFlags.NonPrimitive))) {
-                                errorInfo = saveErrorInfo;
+                                resetErrorInfo(saveErrorInfo);
                                 return result;
                             }
                         }
                         // hi-speed no-this-instantiation check (less accurate, but avoids costly `this`-instantiation when the constraint will suffice), see #28231 for report on why this is needed
                         else if (result = isRelatedTo(constraint, target, /*reportErrors*/ false, /*headMessage*/ undefined, isIntersectionConstituent)) {
-                            errorInfo = saveErrorInfo;
+                            resetErrorInfo(saveErrorInfo);
                             return result;
                         }
                         // slower, fuller, this-instantiated check (necessary when comparing raw `this` types from base classes), see `subclassWithPolymorphicThisIsAssignable.ts` test for example
                         else if (result = isRelatedTo(getTypeWithThisArgument(constraint, source), target, reportErrors, /*headMessage*/ undefined, isIntersectionConstituent)) {
-                            errorInfo = saveErrorInfo;
+                            resetErrorInfo(saveErrorInfo);
                             return result;
                         }
                     }
                 }
                 else if (source.flags & TypeFlags.Index) {
                     if (result = isRelatedTo(keyofConstraintType, target, reportErrors)) {
-                        errorInfo = saveErrorInfo;
+                        resetErrorInfo(saveErrorInfo);
                         return result;
                     }
                 }
@@ -13595,7 +13734,7 @@ namespace ts {
                                 result &= isRelatedTo(getFalseTypeFromConditionalType(<ConditionalType>source), getFalseTypeFromConditionalType(<ConditionalType>target), reportErrors);
                             }
                             if (result) {
-                                errorInfo = saveErrorInfo;
+                                resetErrorInfo(saveErrorInfo);
                                 return result;
                             }
                         }
@@ -13604,14 +13743,14 @@ namespace ts {
                         const distributiveConstraint = getConstraintOfDistributiveConditionalType(<ConditionalType>source);
                         if (distributiveConstraint) {
                             if (result = isRelatedTo(distributiveConstraint, target, reportErrors)) {
-                                errorInfo = saveErrorInfo;
+                                resetErrorInfo(saveErrorInfo);
                                 return result;
                             }
                         }
                         const defaultConstraint = getDefaultConstraintOfConditionalType(<ConditionalType>source);
                         if (defaultConstraint) {
                             if (result = isRelatedTo(defaultConstraint, target, reportErrors)) {
-                                errorInfo = saveErrorInfo;
+                                resetErrorInfo(saveErrorInfo);
                                 return result;
                             }
                         }
@@ -13625,7 +13764,7 @@ namespace ts {
                     if (isGenericMappedType(target)) {
                         if (isGenericMappedType(source)) {
                             if (result = mappedTypeRelatedTo(source, target, reportErrors)) {
-                                errorInfo = saveErrorInfo;
+                                resetErrorInfo(saveErrorInfo);
                                 return result;
                             }
                         }
@@ -13671,7 +13810,7 @@ namespace ts {
                     // relates to X. Thus, we include intersection types on the source side here.
                     if (source.flags & (TypeFlags.Object | TypeFlags.Intersection) && target.flags & TypeFlags.Object) {
                         // Report structural errors only if we haven't reported any errors yet
-                        const reportStructuralErrors = reportErrors && errorInfo === saveErrorInfo && !sourceIsPrimitive;
+                        const reportStructuralErrors = reportErrors && errorInfo === saveErrorInfo.errorInfo && !sourceIsPrimitive;
                         result = propertiesRelatedTo(source, target, reportStructuralErrors, /*excludedProperties*/ undefined, isIntersectionConstituent);
                         if (result) {
                             result &= signaturesRelatedTo(source, target, SignatureKind.Call, reportStructuralErrors);
@@ -13686,7 +13825,7 @@ namespace ts {
                             }
                         }
                         if (varianceCheckFailed && result) {
-                            errorInfo = originalErrorInfo || errorInfo || saveErrorInfo; // Use variance error (there is no structural one) and return false
+                            errorInfo = originalErrorInfo || errorInfo || saveErrorInfo.errorInfo; // Use variance error (there is no structural one) and return false
                         }
                         else if (result) {
                             return result;
@@ -13718,7 +13857,7 @@ namespace ts {
                         // We elide the variance-based error elaborations, since those might not be too helpful, since we'll potentially
                         // be assuming identity of the type parameter.
                         originalErrorInfo = undefined;
-                        errorInfo = saveErrorInfo;
+                        resetErrorInfo(saveErrorInfo);
                         return undefined;
                     }
                     const allowStructuralFallback = targetTypeArguments && hasCovariantVoidArgument(targetTypeArguments, variances);
@@ -13746,7 +13885,7 @@ namespace ts {
                         // comparison unexpectedly succeeds. This can happen when the structural comparison result
                         // is a Ternary.Maybe for example caused by the recursion depth limiter.
                         originalErrorInfo = errorInfo;
-                        errorInfo = saveErrorInfo;
+                        resetErrorInfo(saveErrorInfo);
                     }
                 }
             }
@@ -13980,7 +14119,7 @@ namespace ts {
                 const related = isPropertySymbolTypeRelated(sourceProp, targetProp, getTypeOfSourceProperty, reportErrors, isIntersectionConstituent);
                 if (!related) {
                     if (reportErrors) {
-                        reportError(Diagnostics.Types_of_property_0_are_incompatible, symbolToString(targetProp));
+                        reportIncompatibleError(Diagnostics.Types_of_property_0_are_incompatible, symbolToString(targetProp));
                     }
                     return Ternary.False;
                 }
@@ -14022,8 +14161,8 @@ namespace ts {
                             if (length(unmatchedProperty.declarations)) {
                                 associateRelatedInfo(createDiagnosticForNode(unmatchedProperty.declarations[0], Diagnostics._0_is_declared_here, propName));
                             }
-                            if (shouldSkipElaboration) {
-                                overrideNextErrorInfo = errorInfo;
+                            if (shouldSkipElaboration && errorInfo) {
+                                overrideNextErrorInfo++;
                             }
                         }
                         else if (tryElaborateArrayLikeErrors(source, target, /*reportErrors*/ false)) {
@@ -14033,8 +14172,8 @@ namespace ts {
                             else {
                                 reportError(Diagnostics.Type_0_is_missing_the_following_properties_from_type_1_Colon_2, typeToString(source), typeToString(target), map(props, p => symbolToString(p)).join(", "));
                             }
-                            if (shouldSkipElaboration) {
-                                overrideNextErrorInfo = errorInfo;
+                            if (shouldSkipElaboration && errorInfo) {
+                                overrideNextErrorInfo++;
                             }
                         }
                         // ELSE: No array like or unmatched property error - just issue top level error (errorInfo = undefined)
@@ -14157,7 +14296,8 @@ namespace ts {
                 }
 
                 let result = Ternary.True;
-                const saveErrorInfo = errorInfo;
+                const saveErrorInfo = captureErrorCalculationState();
+                const incompatibleReporter = kind === SignatureKind.Construct ? reportIncompatibleConstructSignatureReturn : reportIncompatibleCallSignatureReturn;
 
                 if (getObjectFlags(source) & ObjectFlags.Instantiated && getObjectFlags(target) & ObjectFlags.Instantiated && source.symbol === target.symbol) {
                     // We have instantiations of the same anonymous type (which typically will be the type of a
@@ -14165,7 +14305,7 @@ namespace ts {
                     // of the much more expensive N * M comparison matrix we explore below. We erase type parameters
                     // as they are known to always be the same.
                     for (let i = 0; i < targetSignatures.length; i++) {
-                        const related = signatureRelatedTo(sourceSignatures[i], targetSignatures[i], /*erase*/ true, reportErrors);
+                        const related = signatureRelatedTo(sourceSignatures[i], targetSignatures[i], /*erase*/ true, reportErrors, incompatibleReporter(sourceSignatures[i], targetSignatures[i]));
                         if (!related) {
                             return Ternary.False;
                         }
@@ -14179,17 +14319,17 @@ namespace ts {
                     // this regardless of the number of signatures, but the potential costs are prohibitive due
                     // to the quadratic nature of the logic below.
                     const eraseGenerics = relation === comparableRelation || !!compilerOptions.noStrictGenericChecks;
-                    result = signatureRelatedTo(sourceSignatures[0], targetSignatures[0], eraseGenerics, reportErrors);
+                    result = signatureRelatedTo(sourceSignatures[0], targetSignatures[0], eraseGenerics, reportErrors, incompatibleReporter(sourceSignatures[0], targetSignatures[0]));
                 }
                 else {
                     outer: for (const t of targetSignatures) {
                         // Only elaborate errors from the first failure
                         let shouldElaborateErrors = reportErrors;
                         for (const s of sourceSignatures) {
-                            const related = signatureRelatedTo(s, t, /*erase*/ true, shouldElaborateErrors);
+                            const related = signatureRelatedTo(s, t, /*erase*/ true, shouldElaborateErrors, incompatibleReporter(s, t));
                             if (related) {
                                 result &= related;
-                                errorInfo = saveErrorInfo;
+                                resetErrorInfo(saveErrorInfo);
                                 continue outer;
                             }
                             shouldElaborateErrors = false;
@@ -14206,12 +14346,26 @@ namespace ts {
                 return result;
             }
 
+            function reportIncompatibleCallSignatureReturn(siga: Signature, sigb: Signature) {
+                if (siga.parameters.length === 0 && sigb.parameters.length === 0) {
+                    return (source: Type, target: Type) => reportIncompatibleError(Diagnostics.Call_signatures_with_no_arguments_have_incompatible_return_types_0_and_1, typeToString(source), typeToString(target));
+                }
+                return (source: Type, target: Type) => reportIncompatibleError(Diagnostics.Call_signature_return_types_0_and_1_are_incompatible, typeToString(source), typeToString(target));
+            }
+
+            function reportIncompatibleConstructSignatureReturn(siga: Signature, sigb: Signature) {
+                if (siga.parameters.length === 0 && sigb.parameters.length === 0) {
+                    return (source: Type, target: Type) => reportIncompatibleError(Diagnostics.Construct_signatures_with_no_arguments_have_incompatible_return_types_0_and_1, typeToString(source), typeToString(target));
+                }
+                return (source: Type, target: Type) => reportIncompatibleError(Diagnostics.Construct_signature_return_types_0_and_1_are_incompatible, typeToString(source), typeToString(target));
+            }
+
             /**
              * See signatureAssignableTo, compareSignaturesIdentical
              */
-            function signatureRelatedTo(source: Signature, target: Signature, erase: boolean, reportErrors: boolean): Ternary {
+            function signatureRelatedTo(source: Signature, target: Signature, erase: boolean, reportErrors: boolean, incompatibleReporter: (source: Type, target: Type) => void): Ternary {
                 return compareSignaturesRelated(erase ? getErasedSignature(source) : source, erase ? getErasedSignature(target) : target,
-                    CallbackCheck.None, /*ignoreReturnTypes*/ false, reportErrors, reportError, isRelatedTo);
+                    CallbackCheck.None, /*ignoreReturnTypes*/ false, reportErrors, reportError, incompatibleReporter, isRelatedTo);
             }
 
             function signaturesIdenticalTo(source: Type, target: Type, kind: SignatureKind): Ternary {
diff --git a/src/compiler/diagnosticMessages.json b/src/compiler/diagnosticMessages.json
index 44bba361bbc..3b219b37de4 100644
--- a/src/compiler/diagnosticMessages.json
+++ b/src/compiler/diagnosticMessages.json
@@ -1040,6 +1040,35 @@
         "code": 1357
     },
 
+    "The types of '{0}' are incompatible between these types.": {
+        "category": "Error",
+        "code": 2200
+    },
+    "The types returned by '{0}' are incompatible between these types.": {
+        "category": "Error",
+        "code": 2201
+    },
+    "Call signature return types '{0}' and '{1}' are incompatible.": {
+        "category": "Error",
+        "code": 2202,
+        "elidedInCompatabilityPyramid": true
+    },
+    "Construct signature return types '{0}' and '{1}' are incompatible.": {
+        "category": "Error",
+        "code": 2203,
+        "elidedInCompatabilityPyramid": true
+    },
+    "Call signatures with no arguments have incompatible return types '{0}' and '{1}'.": {
+        "category": "Error",
+        "code": 2204,
+        "elidedInCompatabilityPyramid": true
+    },
+    "Construct signatures with no arguments have incompatible return types '{0}' and '{1}'.": {
+        "category": "Error",
+        "code": 2205,
+        "elidedInCompatabilityPyramid": true
+    },
+
     "Duplicate identifier '{0}'.": {
         "category": "Error",
         "code": 2300
diff --git a/src/compiler/types.ts b/src/compiler/types.ts
index e20518ed119..eb568ed5cff 100644
--- a/src/compiler/types.ts
+++ b/src/compiler/types.ts
@@ -4631,6 +4631,8 @@ namespace ts {
         code: number;
         message: string;
         reportsUnnecessary?: {};
+        /* @internal */
+        elidedInCompatabilityPyramid?: boolean;
     }
 
     /**
diff --git a/tests/baselines/reference/arrayLiterals3.errors.txt b/tests/baselines/reference/arrayLiterals3.errors.txt
index 4d398978c96..5f592b74f3e 100644
--- a/tests/baselines/reference/arrayLiterals3.errors.txt
+++ b/tests/baselines/reference/arrayLiterals3.errors.txt
@@ -8,10 +8,9 @@ tests/cases/conformance/expressions/arrayLiterals/arrayLiterals3.ts(17,5): error
 tests/cases/conformance/expressions/arrayLiterals/arrayLiterals3.ts(32,5): error TS2739: Type '(number[] | string[])[]' is missing the following properties from type 'tup': 0, 1
 tests/cases/conformance/expressions/arrayLiterals/arrayLiterals3.ts(33,5): error TS2739: Type 'number[]' is missing the following properties from type '[number, number, number]': 0, 1, 2
 tests/cases/conformance/expressions/arrayLiterals/arrayLiterals3.ts(34,5): error TS2322: Type '(string | number)[]' is not assignable to type 'myArray'.
-  Types of property 'pop' are incompatible.
-    Type '() => string | number' is not assignable to type '() => Number'.
-      Type 'string | number' is not assignable to type 'Number'.
-        Type 'string' is not assignable to type 'Number'.
+  The types returned by 'pop()' are incompatible between these types.
+    Type 'string | number' is not assignable to type 'Number'.
+      Type 'string' is not assignable to type 'Number'.
 
 
 ==== tests/cases/conformance/expressions/arrayLiterals/arrayLiterals3.ts (8 errors) ====
@@ -67,8 +66,7 @@ tests/cases/conformance/expressions/arrayLiterals/arrayLiterals3.ts(34,5): error
     var c2: myArray = [...temp1, ...temp];            // Error cannot assign (number|string)[] to number[]
         ~~
 !!! error TS2322: Type '(string | number)[]' is not assignable to type 'myArray'.
-!!! error TS2322:   Types of property 'pop' are incompatible.
-!!! error TS2322:     Type '() => string | number' is not assignable to type '() => Number'.
-!!! error TS2322:       Type 'string | number' is not assignable to type 'Number'.
-!!! error TS2322:         Type 'string' is not assignable to type 'Number'.
+!!! error TS2322:   The types returned by 'pop()' are incompatible between these types.
+!!! error TS2322:     Type 'string | number' is not assignable to type 'Number'.
+!!! error TS2322:       Type 'string' is not assignable to type 'Number'.
     
\ No newline at end of file
diff --git a/tests/baselines/reference/arrayOfSubtypeIsAssignableToReadonlyArray.errors.txt b/tests/baselines/reference/arrayOfSubtypeIsAssignableToReadonlyArray.errors.txt
index 63d3a6f7b64..66b3c2c8691 100644
--- a/tests/baselines/reference/arrayOfSubtypeIsAssignableToReadonlyArray.errors.txt
+++ b/tests/baselines/reference/arrayOfSubtypeIsAssignableToReadonlyArray.errors.txt
@@ -1,10 +1,9 @@
 tests/cases/compiler/arrayOfSubtypeIsAssignableToReadonlyArray.ts(13,1): error TS2322: Type 'A[]' is not assignable to type 'readonly B[]'.
   Property 'b' is missing in type 'A' but required in type 'B'.
 tests/cases/compiler/arrayOfSubtypeIsAssignableToReadonlyArray.ts(18,1): error TS2322: Type 'C<A>' is not assignable to type 'readonly B[]'.
-  Types of property 'concat' are incompatible.
-    Type '{ (...items: ConcatArray<A>[]): A[]; (...items: (A | ConcatArray<A>)[]): A[]; }' is not assignable to type '{ (...items: ConcatArray<B>[]): B[]; (...items: (B | ConcatArray<B>)[]): B[]; }'.
-      Type 'A[]' is not assignable to type 'B[]'.
-        Type 'A' is not assignable to type 'B'.
+  The types returned by 'concat(...)' are incompatible between these types.
+    Type 'A[]' is not assignable to type 'B[]'.
+      Type 'A' is not assignable to type 'B'.
 
 
 ==== tests/cases/compiler/arrayOfSubtypeIsAssignableToReadonlyArray.ts (2 errors) ====
@@ -32,8 +31,7 @@ tests/cases/compiler/arrayOfSubtypeIsAssignableToReadonlyArray.ts(18,1): error T
     rrb = cra; // error: 'A' is not assignable to 'B'
     ~~~
 !!! error TS2322: Type 'C<A>' is not assignable to type 'readonly B[]'.
-!!! error TS2322:   Types of property 'concat' are incompatible.
-!!! error TS2322:     Type '{ (...items: ConcatArray<A>[]): A[]; (...items: (A | ConcatArray<A>)[]): A[]; }' is not assignable to type '{ (...items: ConcatArray<B>[]): B[]; (...items: (B | ConcatArray<B>)[]): B[]; }'.
-!!! error TS2322:       Type 'A[]' is not assignable to type 'B[]'.
-!!! error TS2322:         Type 'A' is not assignable to type 'B'.
+!!! error TS2322:   The types returned by 'concat(...)' are incompatible between these types.
+!!! error TS2322:     Type 'A[]' is not assignable to type 'B[]'.
+!!! error TS2322:       Type 'A' is not assignable to type 'B'.
     
\ No newline at end of file
diff --git a/tests/baselines/reference/assignFromBooleanInterface2.errors.txt b/tests/baselines/reference/assignFromBooleanInterface2.errors.txt
index 6c7ebbe5ee8..ba8b2f5a9c9 100644
--- a/tests/baselines/reference/assignFromBooleanInterface2.errors.txt
+++ b/tests/baselines/reference/assignFromBooleanInterface2.errors.txt
@@ -1,7 +1,6 @@
 tests/cases/conformance/types/primitives/boolean/assignFromBooleanInterface2.ts(14,1): error TS2322: Type 'NotBoolean' is not assignable to type 'Boolean'.
-  Types of property 'valueOf' are incompatible.
-    Type '() => Object' is not assignable to type '() => boolean'.
-      Type 'Object' is not assignable to type 'boolean'.
+  The types returned by 'valueOf()' are incompatible between these types.
+    Type 'Object' is not assignable to type 'boolean'.
 tests/cases/conformance/types/primitives/boolean/assignFromBooleanInterface2.ts(19,1): error TS2322: Type 'Boolean' is not assignable to type 'boolean'.
   'boolean' is a primitive, but 'Boolean' is a wrapper object. Prefer using 'boolean' when possible.
 tests/cases/conformance/types/primitives/boolean/assignFromBooleanInterface2.ts(20,1): error TS2322: Type 'NotBoolean' is not assignable to type 'boolean'.
@@ -24,9 +23,8 @@ tests/cases/conformance/types/primitives/boolean/assignFromBooleanInterface2.ts(
     a = b;
     ~
 !!! error TS2322: Type 'NotBoolean' is not assignable to type 'Boolean'.
-!!! error TS2322:   Types of property 'valueOf' are incompatible.
-!!! error TS2322:     Type '() => Object' is not assignable to type '() => boolean'.
-!!! error TS2322:       Type 'Object' is not assignable to type 'boolean'.
+!!! error TS2322:   The types returned by 'valueOf()' are incompatible between these types.
+!!! error TS2322:     Type 'Object' is not assignable to type 'boolean'.
     
     b = a;
     b = x;
diff --git a/tests/baselines/reference/asyncFunctionDeclaration15_es5.errors.txt b/tests/baselines/reference/asyncFunctionDeclaration15_es5.errors.txt
index 6b4b0a71c6f..7e3595ec6f4 100644
--- a/tests/baselines/reference/asyncFunctionDeclaration15_es5.errors.txt
+++ b/tests/baselines/reference/asyncFunctionDeclaration15_es5.errors.txt
@@ -5,10 +5,9 @@ tests/cases/conformance/async/es5/functionDeclarations/asyncFunctionDeclaration1
 tests/cases/conformance/async/es5/functionDeclarations/asyncFunctionDeclaration15_es5.ts(8,23): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
 tests/cases/conformance/async/es5/functionDeclarations/asyncFunctionDeclaration15_es5.ts(9,23): error TS1055: Type 'PromiseLike' is not a valid async function return type in ES5/ES3 because it does not refer to a Promise-compatible constructor value.
 tests/cases/conformance/async/es5/functionDeclarations/asyncFunctionDeclaration15_es5.ts(10,23): error TS1055: Type 'typeof Thenable' is not a valid async function return type in ES5/ES3 because it does not refer to a Promise-compatible constructor value.
-  Type 'Thenable' is not assignable to type 'PromiseLike<T>'.
-    Types of property 'then' are incompatible.
-      Type '() => void' is not assignable to type '<TResult1 = T, TResult2 = never>(onfulfilled?: (value: T) => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => PromiseLike<TResult1 | TResult2>'.
-        Type 'void' is not assignable to type 'PromiseLike<TResult1 | TResult2>'.
+  Construct signature return types 'Thenable' and 'PromiseLike<T>' are incompatible.
+    The types returned by 'then(...)' are incompatible between these types.
+      Type 'void' is not assignable to type 'PromiseLike<TResult1 | TResult2>'.
 tests/cases/conformance/async/es5/functionDeclarations/asyncFunctionDeclaration15_es5.ts(17,16): error TS1058: The return type of an async function must either be a valid promise or must not contain a callable 'then' member.
 tests/cases/conformance/async/es5/functionDeclarations/asyncFunctionDeclaration15_es5.ts(23,25): error TS1320: Type of 'await' operand must either be a valid promise or must not contain a callable 'then' member.
 
@@ -38,10 +37,9 @@ tests/cases/conformance/async/es5/functionDeclarations/asyncFunctionDeclaration1
     async function fn6(): Thenable { } // error
                           ~~~~~~~~
 !!! error TS1055: Type 'typeof Thenable' is not a valid async function return type in ES5/ES3 because it does not refer to a Promise-compatible constructor value.
-!!! error TS1055:   Type 'Thenable' is not assignable to type 'PromiseLike<T>'.
-!!! error TS1055:     Types of property 'then' are incompatible.
-!!! error TS1055:       Type '() => void' is not assignable to type '<TResult1 = T, TResult2 = never>(onfulfilled?: (value: T) => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => PromiseLike<TResult1 | TResult2>'.
-!!! error TS1055:         Type 'void' is not assignable to type 'PromiseLike<TResult1 | TResult2>'.
+!!! error TS1055:   Construct signature return types 'Thenable' and 'PromiseLike<T>' are incompatible.
+!!! error TS1055:     The types returned by 'then(...)' are incompatible between these types.
+!!! error TS1055:       Type 'void' is not assignable to type 'PromiseLike<TResult1 | TResult2>'.
     async function fn7() { return; } // valid: Promise<void>
     async function fn8() { return 1; } // valid: Promise<number>
     async function fn9() { return null; } // valid: Promise<any>
diff --git a/tests/baselines/reference/bigintWithLib.errors.txt b/tests/baselines/reference/bigintWithLib.errors.txt
index b4c9f65cf9c..fb54c2a530b 100644
--- a/tests/baselines/reference/bigintWithLib.errors.txt
+++ b/tests/baselines/reference/bigintWithLib.errors.txt
@@ -4,15 +4,11 @@ tests/cases/compiler/bigintWithLib.ts(16,33): error TS2769: No overload matches
     Argument of type 'number[]' is not assignable to parameter of type 'number'.
   Overload 2 of 3, '(array: Iterable<bigint>): BigInt64Array', gave the following error.
     Argument of type 'number[]' is not assignable to parameter of type 'Iterable<bigint>'.
-      Types of property '[Symbol.iterator]' are incompatible.
-        Type '() => IterableIterator<number>' is not assignable to type '() => Iterator<bigint, any, undefined>'.
-          Type 'IterableIterator<number>' is not assignable to type 'Iterator<bigint, any, undefined>'.
-            Types of property 'next' are incompatible.
-              Type '(...args: [] | [undefined]) => IteratorResult<number, any>' is not assignable to type '(...args: [] | [undefined]) => IteratorResult<bigint, any>'.
-                Type 'IteratorResult<number, any>' is not assignable to type 'IteratorResult<bigint, any>'.
-                  Type 'IteratorYieldResult<number>' is not assignable to type 'IteratorResult<bigint, any>'.
-                    Type 'IteratorYieldResult<number>' is not assignable to type 'IteratorYieldResult<bigint>'.
-                      Type 'number' is not assignable to type 'bigint'.
+      The types returned by '[Symbol.iterator]().next(...)' are incompatible between these types.
+        Type 'IteratorResult<number, any>' is not assignable to type 'IteratorResult<bigint, any>'.
+          Type 'IteratorYieldResult<number>' is not assignable to type 'IteratorResult<bigint, any>'.
+            Type 'IteratorYieldResult<number>' is not assignable to type 'IteratorYieldResult<bigint>'.
+              Type 'number' is not assignable to type 'bigint'.
   Overload 3 of 3, '(buffer: ArrayBuffer | SharedArrayBuffer, byteOffset?: number, length?: number): BigInt64Array', gave the following error.
     Argument of type 'number[]' is not assignable to parameter of type 'ArrayBuffer | SharedArrayBuffer'.
       Type 'number[]' is missing the following properties from type 'SharedArrayBuffer': byteLength, [Symbol.species], [Symbol.toStringTag]
@@ -55,15 +51,11 @@ tests/cases/compiler/bigintWithLib.ts(43,26): error TS2345: Argument of type '12
 !!! error TS2769:     Argument of type 'number[]' is not assignable to parameter of type 'number'.
 !!! error TS2769:   Overload 2 of 3, '(array: Iterable<bigint>): BigInt64Array', gave the following error.
 !!! error TS2769:     Argument of type 'number[]' is not assignable to parameter of type 'Iterable<bigint>'.
-!!! error TS2769:       Types of property '[Symbol.iterator]' are incompatible.
-!!! error TS2769:         Type '() => IterableIterator<number>' is not assignable to type '() => Iterator<bigint, any, undefined>'.
-!!! error TS2769:           Type 'IterableIterator<number>' is not assignable to type 'Iterator<bigint, any, undefined>'.
-!!! error TS2769:             Types of property 'next' are incompatible.
-!!! error TS2769:               Type '(...args: [] | [undefined]) => IteratorResult<number, any>' is not assignable to type '(...args: [] | [undefined]) => IteratorResult<bigint, any>'.
-!!! error TS2769:                 Type 'IteratorResult<number, any>' is not assignable to type 'IteratorResult<bigint, any>'.
-!!! error TS2769:                   Type 'IteratorYieldResult<number>' is not assignable to type 'IteratorResult<bigint, any>'.
-!!! error TS2769:                     Type 'IteratorYieldResult<number>' is not assignable to type 'IteratorYieldResult<bigint>'.
-!!! error TS2769:                       Type 'number' is not assignable to type 'bigint'.
+!!! error TS2769:       The types returned by '[Symbol.iterator]().next(...)' are incompatible between these types.
+!!! error TS2769:         Type 'IteratorResult<number, any>' is not assignable to type 'IteratorResult<bigint, any>'.
+!!! error TS2769:           Type 'IteratorYieldResult<number>' is not assignable to type 'IteratorResult<bigint, any>'.
+!!! error TS2769:             Type 'IteratorYieldResult<number>' is not assignable to type 'IteratorYieldResult<bigint>'.
+!!! error TS2769:               Type 'number' is not assignable to type 'bigint'.
 !!! error TS2769:   Overload 3 of 3, '(buffer: ArrayBuffer | SharedArrayBuffer, byteOffset?: number, length?: number): BigInt64Array', gave the following error.
 !!! error TS2769:     Argument of type 'number[]' is not assignable to parameter of type 'ArrayBuffer | SharedArrayBuffer'.
 !!! error TS2769:       Type 'number[]' is missing the following properties from type 'SharedArrayBuffer': byteLength, [Symbol.species], [Symbol.toStringTag]
diff --git a/tests/baselines/reference/booleanAssignment.errors.txt b/tests/baselines/reference/booleanAssignment.errors.txt
index fc25fd4007f..8a928c57404 100644
--- a/tests/baselines/reference/booleanAssignment.errors.txt
+++ b/tests/baselines/reference/booleanAssignment.errors.txt
@@ -1,9 +1,8 @@
 tests/cases/compiler/booleanAssignment.ts(2,1): error TS2322: Type '1' is not assignable to type 'Boolean'.
 tests/cases/compiler/booleanAssignment.ts(3,1): error TS2322: Type '"a"' is not assignable to type 'Boolean'.
 tests/cases/compiler/booleanAssignment.ts(4,1): error TS2322: Type '{}' is not assignable to type 'Boolean'.
-  Types of property 'valueOf' are incompatible.
-    Type '() => Object' is not assignable to type '() => boolean'.
-      Type 'Object' is not assignable to type 'boolean'.
+  The types returned by 'valueOf()' are incompatible between these types.
+    Type 'Object' is not assignable to type 'boolean'.
 
 
 ==== tests/cases/compiler/booleanAssignment.ts (3 errors) ====
@@ -17,9 +16,8 @@ tests/cases/compiler/booleanAssignment.ts(4,1): error TS2322: Type '{}' is not a
     b = {}; // Error
     ~
 !!! error TS2322: Type '{}' is not assignable to type 'Boolean'.
-!!! error TS2322:   Types of property 'valueOf' are incompatible.
-!!! error TS2322:     Type '() => Object' is not assignable to type '() => boolean'.
-!!! error TS2322:       Type 'Object' is not assignable to type 'boolean'.
+!!! error TS2322:   The types returned by 'valueOf()' are incompatible between these types.
+!!! error TS2322:     Type 'Object' is not assignable to type 'boolean'.
     
     var o = {};
     o = b; // OK
diff --git a/tests/baselines/reference/callSignatureAssignabilityInInheritance.errors.txt b/tests/baselines/reference/callSignatureAssignabilityInInheritance.errors.txt
index 2ca3bb1aaf0..43589e94370 100644
--- a/tests/baselines/reference/callSignatureAssignabilityInInheritance.errors.txt
+++ b/tests/baselines/reference/callSignatureAssignabilityInInheritance.errors.txt
@@ -1,12 +1,10 @@
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/callSignatureAssignabilityInInheritance.ts(57,15): error TS2430: Interface 'I2' incorrectly extends interface 'Base2'.
-  Types of property 'a' are incompatible.
-    Type '(x: number) => string' is not assignable to type '(x: number) => number'.
-      Type 'string' is not assignable to type 'number'.
+  The types returned by 'a(...)' are incompatible between these types.
+    Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/callSignatureAssignabilityInInheritance.ts(63,15): error TS2430: Interface 'I3' incorrectly extends interface 'Base2'.
-  Types of property 'a2' are incompatible.
-    Type '<T>(x: T) => string' is not assignable to type '<T>(x: T) => T'.
-      Type 'string' is not assignable to type 'T'.
-        'string' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+  The types returned by 'a2(...)' are incompatible between these types.
+    Type 'string' is not assignable to type 'T'.
+      'string' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
 
 
 ==== tests/cases/conformance/types/typeRelationships/assignmentCompatibility/callSignatureAssignabilityInInheritance.ts (2 errors) ====
@@ -69,9 +67,8 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/callSign
         interface I2 extends Base2 {
                   ~~
 !!! error TS2430: Interface 'I2' incorrectly extends interface 'Base2'.
-!!! error TS2430:   Types of property 'a' are incompatible.
-!!! error TS2430:     Type '(x: number) => string' is not assignable to type '(x: number) => number'.
-!!! error TS2430:       Type 'string' is not assignable to type 'number'.
+!!! error TS2430:   The types returned by 'a(...)' are incompatible between these types.
+!!! error TS2430:     Type 'string' is not assignable to type 'number'.
             // N's
             a: (x: number) => string; // error because base returns non-void;
         }
@@ -80,10 +77,9 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/callSign
         interface I3 extends Base2 {
                   ~~
 !!! error TS2430: Interface 'I3' incorrectly extends interface 'Base2'.
-!!! error TS2430:   Types of property 'a2' are incompatible.
-!!! error TS2430:     Type '<T>(x: T) => string' is not assignable to type '<T>(x: T) => T'.
-!!! error TS2430:       Type 'string' is not assignable to type 'T'.
-!!! error TS2430:         'string' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+!!! error TS2430:   The types returned by 'a2(...)' are incompatible between these types.
+!!! error TS2430:     Type 'string' is not assignable to type 'T'.
+!!! error TS2430:       'string' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
             // N's
             a2: <T>(x: T) => string; // error because base returns non-void;
         }
diff --git a/tests/baselines/reference/callSignatureAssignabilityInInheritance3.errors.txt b/tests/baselines/reference/callSignatureAssignabilityInInheritance3.errors.txt
index 671c09b3d79..287875d44da 100644
--- a/tests/baselines/reference/callSignatureAssignabilityInInheritance3.errors.txt
+++ b/tests/baselines/reference/callSignatureAssignabilityInInheritance3.errors.txt
@@ -27,16 +27,14 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/callSign
           Types of property 'a' are incompatible.
             Type 'string' is not assignable to type 'Base'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/callSignatureAssignabilityInInheritance3.ts(100,19): error TS2430: Interface 'I6' incorrectly extends interface 'B'.
-  Types of property 'a2' are incompatible.
-    Type '<T>(x: T) => string[]' is not assignable to type '<T>(x: T) => T[]'.
-      Type 'string[]' is not assignable to type 'T[]'.
-        Type 'string' is not assignable to type 'T'.
-          'string' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+  The types returned by 'a2(...)' are incompatible between these types.
+    Type 'string[]' is not assignable to type 'T[]'.
+      Type 'string' is not assignable to type 'T'.
+        'string' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/callSignatureAssignabilityInInheritance3.ts(109,19): error TS2430: Interface 'I7' incorrectly extends interface 'C'.
-  Types of property 'a2' are incompatible.
-    Type '<T>(x: T) => T[]' is not assignable to type '<T>(x: T) => string[]'.
-      Type 'T[]' is not assignable to type 'string[]'.
-        Type 'T' is not assignable to type 'string'.
+  The types returned by 'a2(...)' are incompatible between these types.
+    Type 'T[]' is not assignable to type 'string[]'.
+      Type 'T' is not assignable to type 'string'.
 
 
 ==== tests/cases/conformance/types/typeRelationships/assignmentCompatibility/callSignatureAssignabilityInInheritance3.ts (6 errors) ====
@@ -174,11 +172,10 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/callSign
             interface I6 extends B {
                       ~~
 !!! error TS2430: Interface 'I6' incorrectly extends interface 'B'.
-!!! error TS2430:   Types of property 'a2' are incompatible.
-!!! error TS2430:     Type '<T>(x: T) => string[]' is not assignable to type '<T>(x: T) => T[]'.
-!!! error TS2430:       Type 'string[]' is not assignable to type 'T[]'.
-!!! error TS2430:         Type 'string' is not assignable to type 'T'.
-!!! error TS2430:           'string' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+!!! error TS2430:   The types returned by 'a2(...)' are incompatible between these types.
+!!! error TS2430:     Type 'string[]' is not assignable to type 'T[]'.
+!!! error TS2430:       Type 'string' is not assignable to type 'T'.
+!!! error TS2430:         'string' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
                 a2: <T>(x: T) => string[]; // error
             }
     
@@ -190,10 +187,9 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/callSign
             interface I7 extends C {
                       ~~
 !!! error TS2430: Interface 'I7' incorrectly extends interface 'C'.
-!!! error TS2430:   Types of property 'a2' are incompatible.
-!!! error TS2430:     Type '<T>(x: T) => T[]' is not assignable to type '<T>(x: T) => string[]'.
-!!! error TS2430:       Type 'T[]' is not assignable to type 'string[]'.
-!!! error TS2430:         Type 'T' is not assignable to type 'string'.
+!!! error TS2430:   The types returned by 'a2(...)' are incompatible between these types.
+!!! error TS2430:     Type 'T[]' is not assignable to type 'string[]'.
+!!! error TS2430:       Type 'T' is not assignable to type 'string'.
                 a2: <T>(x: T) => T[]; // error
             }
         }
diff --git a/tests/baselines/reference/checkJsxChildrenCanBeTupleType.errors.txt b/tests/baselines/reference/checkJsxChildrenCanBeTupleType.errors.txt
index aeaeb56ea75..0780f4e92c1 100644
--- a/tests/baselines/reference/checkJsxChildrenCanBeTupleType.errors.txt
+++ b/tests/baselines/reference/checkJsxChildrenCanBeTupleType.errors.txt
@@ -1,10 +1,8 @@
 tests/cases/conformance/jsx/checkJsxChildrenCanBeTupleType.tsx(17,18): error TS2769: No overload matches this call.
   Overload 1 of 2, '(props: Readonly<ResizablePanelProps>): ResizablePanel', gave the following error.
     Type '{ children: [Element, Element, Element]; }' is not assignable to type 'Readonly<ResizablePanelProps>'.
-      Types of property 'children' are incompatible.
-        Type '[Element, Element, Element]' is not assignable to type '[ReactNode, ReactNode]'.
-          Types of property 'length' are incompatible.
-            Type '3' is not assignable to type '2'.
+      The types of 'children.length' are incompatible between these types.
+        Type '3' is not assignable to type '2'.
   Overload 2 of 2, '(props: ResizablePanelProps, context?: any): ResizablePanel', gave the following error.
     Type '{ children: [Element, Element, Element]; }' is not assignable to type 'Readonly<ResizablePanelProps>'.
       Types of property 'children' are incompatible.
@@ -33,10 +31,8 @@ tests/cases/conformance/jsx/checkJsxChildrenCanBeTupleType.tsx(17,18): error TS2
 !!! error TS2769: No overload matches this call.
 !!! error TS2769:   Overload 1 of 2, '(props: Readonly<ResizablePanelProps>): ResizablePanel', gave the following error.
 !!! error TS2769:     Type '{ children: [Element, Element, Element]; }' is not assignable to type 'Readonly<ResizablePanelProps>'.
-!!! error TS2769:       Types of property 'children' are incompatible.
-!!! error TS2769:         Type '[Element, Element, Element]' is not assignable to type '[ReactNode, ReactNode]'.
-!!! error TS2769:           Types of property 'length' are incompatible.
-!!! error TS2769:             Type '3' is not assignable to type '2'.
+!!! error TS2769:       The types of 'children.length' are incompatible between these types.
+!!! error TS2769:         Type '3' is not assignable to type '2'.
 !!! error TS2769:   Overload 2 of 2, '(props: ResizablePanelProps, context?: any): ResizablePanel', gave the following error.
 !!! error TS2769:     Type '{ children: [Element, Element, Element]; }' is not assignable to type 'Readonly<ResizablePanelProps>'.
 !!! error TS2769:       Types of property 'children' are incompatible.
diff --git a/tests/baselines/reference/complexRecursiveCollections.errors.txt b/tests/baselines/reference/complexRecursiveCollections.errors.txt
index 27bb24bc5cc..cd88e596fd1 100644
--- a/tests/baselines/reference/complexRecursiveCollections.errors.txt
+++ b/tests/baselines/reference/complexRecursiveCollections.errors.txt
@@ -1,18 +1,15 @@
 tests/cases/compiler/immutable.ts(341,22): error TS2430: Interface 'Keyed<K, V>' incorrectly extends interface 'Collection<K, V>'.
-  Types of property 'toSeq' are incompatible.
-    Type '() => Keyed<K, V>' is not assignable to type '() => this'.
-      Type 'Keyed<K, V>' is not assignable to type 'this'.
-        'Keyed<K, V>' is assignable to the constraint of type 'this', but 'this' could be instantiated with a different subtype of constraint 'Keyed<K, V>'.
+  The types returned by 'toSeq()' are incompatible between these types.
+    Type 'Keyed<K, V>' is not assignable to type 'this'.
+      'Keyed<K, V>' is assignable to the constraint of type 'this', but 'this' could be instantiated with a different subtype of constraint 'Keyed<K, V>'.
 tests/cases/compiler/immutable.ts(359,22): error TS2430: Interface 'Indexed<T>' incorrectly extends interface 'Collection<number, T>'.
-  Types of property 'toSeq' are incompatible.
-    Type '() => Indexed<T>' is not assignable to type '() => this'.
-      Type 'Indexed<T>' is not assignable to type 'this'.
-        'Indexed<T>' is assignable to the constraint of type 'this', but 'this' could be instantiated with a different subtype of constraint 'Indexed<T>'.
+  The types returned by 'toSeq()' are incompatible between these types.
+    Type 'Indexed<T>' is not assignable to type 'this'.
+      'Indexed<T>' is assignable to the constraint of type 'this', but 'this' could be instantiated with a different subtype of constraint 'Indexed<T>'.
 tests/cases/compiler/immutable.ts(391,22): error TS2430: Interface 'Set<T>' incorrectly extends interface 'Collection<never, T>'.
-  Types of property 'toSeq' are incompatible.
-    Type '() => Set<T>' is not assignable to type '() => this'.
-      Type 'Set<T>' is not assignable to type 'this'.
-        'Set<T>' is assignable to the constraint of type 'this', but 'this' could be instantiated with a different subtype of constraint 'Set<T>'.
+  The types returned by 'toSeq()' are incompatible between these types.
+    Type 'Set<T>' is not assignable to type 'this'.
+      'Set<T>' is assignable to the constraint of type 'this', but 'this' could be instantiated with a different subtype of constraint 'Set<T>'.
 
 
 ==== tests/cases/compiler/complex.ts (0 errors) ====
@@ -380,10 +377,9 @@ tests/cases/compiler/immutable.ts(391,22): error TS2430: Interface 'Set<T>' inco
         export interface Keyed<K, V> extends Collection<K, V> {
                          ~~~~~
 !!! error TS2430: Interface 'Keyed<K, V>' incorrectly extends interface 'Collection<K, V>'.
-!!! error TS2430:   Types of property 'toSeq' are incompatible.
-!!! error TS2430:     Type '() => Keyed<K, V>' is not assignable to type '() => this'.
-!!! error TS2430:       Type 'Keyed<K, V>' is not assignable to type 'this'.
-!!! error TS2430:         'Keyed<K, V>' is assignable to the constraint of type 'this', but 'this' could be instantiated with a different subtype of constraint 'Keyed<K, V>'.
+!!! error TS2430:   The types returned by 'toSeq()' are incompatible between these types.
+!!! error TS2430:     Type 'Keyed<K, V>' is not assignable to type 'this'.
+!!! error TS2430:       'Keyed<K, V>' is assignable to the constraint of type 'this', but 'this' could be instantiated with a different subtype of constraint 'Keyed<K, V>'.
           toJS(): Object;
           toJSON(): { [key: string]: V };
           toSeq(): Seq.Keyed<K, V>;
@@ -404,10 +400,9 @@ tests/cases/compiler/immutable.ts(391,22): error TS2430: Interface 'Set<T>' inco
         export interface Indexed<T> extends Collection<number, T> {
                          ~~~~~~~
 !!! error TS2430: Interface 'Indexed<T>' incorrectly extends interface 'Collection<number, T>'.
-!!! error TS2430:   Types of property 'toSeq' are incompatible.
-!!! error TS2430:     Type '() => Indexed<T>' is not assignable to type '() => this'.
-!!! error TS2430:       Type 'Indexed<T>' is not assignable to type 'this'.
-!!! error TS2430:         'Indexed<T>' is assignable to the constraint of type 'this', but 'this' could be instantiated with a different subtype of constraint 'Indexed<T>'.
+!!! error TS2430:   The types returned by 'toSeq()' are incompatible between these types.
+!!! error TS2430:     Type 'Indexed<T>' is not assignable to type 'this'.
+!!! error TS2430:       'Indexed<T>' is assignable to the constraint of type 'this', but 'this' could be instantiated with a different subtype of constraint 'Indexed<T>'.
           toJS(): Array<any>;
           toJSON(): Array<T>;
           // Reading values
@@ -442,10 +437,9 @@ tests/cases/compiler/immutable.ts(391,22): error TS2430: Interface 'Set<T>' inco
         export interface Set<T> extends Collection<never, T> {
                          ~~~
 !!! error TS2430: Interface 'Set<T>' incorrectly extends interface 'Collection<never, T>'.
-!!! error TS2430:   Types of property 'toSeq' are incompatible.
-!!! error TS2430:     Type '() => Set<T>' is not assignable to type '() => this'.
-!!! error TS2430:       Type 'Set<T>' is not assignable to type 'this'.
-!!! error TS2430:         'Set<T>' is assignable to the constraint of type 'this', but 'this' could be instantiated with a different subtype of constraint 'Set<T>'.
+!!! error TS2430:   The types returned by 'toSeq()' are incompatible between these types.
+!!! error TS2430:     Type 'Set<T>' is not assignable to type 'this'.
+!!! error TS2430:       'Set<T>' is assignable to the constraint of type 'this', but 'this' could be instantiated with a different subtype of constraint 'Set<T>'.
           toJS(): Array<any>;
           toJSON(): Array<T>;
           toSeq(): Seq.Set<T>;
diff --git a/tests/baselines/reference/constructSignatureAssignabilityInInheritance.errors.txt b/tests/baselines/reference/constructSignatureAssignabilityInInheritance.errors.txt
index e326d163c8c..1cc019746ba 100644
--- a/tests/baselines/reference/constructSignatureAssignabilityInInheritance.errors.txt
+++ b/tests/baselines/reference/constructSignatureAssignabilityInInheritance.errors.txt
@@ -1,12 +1,10 @@
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/constructSignatureAssignabilityInInheritance.ts(61,15): error TS2430: Interface 'I2' incorrectly extends interface 'Base2'.
-  Types of property 'a' are incompatible.
-    Type 'new (x: number) => string' is not assignable to type 'new (x: number) => number'.
-      Type 'string' is not assignable to type 'number'.
+  The types returned by 'new a(...)' are incompatible between these types.
+    Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/constructSignatureAssignabilityInInheritance.ts(67,15): error TS2430: Interface 'I3' incorrectly extends interface 'Base2'.
-  Types of property 'a2' are incompatible.
-    Type 'new <T>(x: T) => string' is not assignable to type 'new <T>(x: T) => T'.
-      Type 'string' is not assignable to type 'T'.
-        'string' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+  The types returned by 'new a2(...)' are incompatible between these types.
+    Type 'string' is not assignable to type 'T'.
+      'string' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
 
 
 ==== tests/cases/conformance/types/typeRelationships/assignmentCompatibility/constructSignatureAssignabilityInInheritance.ts (2 errors) ====
@@ -73,9 +71,8 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/construc
         interface I2 extends Base2 {
                   ~~
 !!! error TS2430: Interface 'I2' incorrectly extends interface 'Base2'.
-!!! error TS2430:   Types of property 'a' are incompatible.
-!!! error TS2430:     Type 'new (x: number) => string' is not assignable to type 'new (x: number) => number'.
-!!! error TS2430:       Type 'string' is not assignable to type 'number'.
+!!! error TS2430:   The types returned by 'new a(...)' are incompatible between these types.
+!!! error TS2430:     Type 'string' is not assignable to type 'number'.
             // N's
             a: new (x: number) => string; // error because base returns non-void;
         }
@@ -84,10 +81,9 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/construc
         interface I3 extends Base2 {
                   ~~
 !!! error TS2430: Interface 'I3' incorrectly extends interface 'Base2'.
-!!! error TS2430:   Types of property 'a2' are incompatible.
-!!! error TS2430:     Type 'new <T>(x: T) => string' is not assignable to type 'new <T>(x: T) => T'.
-!!! error TS2430:       Type 'string' is not assignable to type 'T'.
-!!! error TS2430:         'string' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+!!! error TS2430:   The types returned by 'new a2(...)' are incompatible between these types.
+!!! error TS2430:     Type 'string' is not assignable to type 'T'.
+!!! error TS2430:       'string' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
             // N's
             a2: new <T>(x: T) => string; // error because base returns non-void;
         }
diff --git a/tests/baselines/reference/constructSignatureAssignabilityInInheritance3.errors.txt b/tests/baselines/reference/constructSignatureAssignabilityInInheritance3.errors.txt
index 59d8105c59c..d4c9e808200 100644
--- a/tests/baselines/reference/constructSignatureAssignabilityInInheritance3.errors.txt
+++ b/tests/baselines/reference/constructSignatureAssignabilityInInheritance3.errors.txt
@@ -27,16 +27,14 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/construc
           Types of property 'a' are incompatible.
             Type 'string' is not assignable to type 'Base'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/constructSignatureAssignabilityInInheritance3.ts(86,19): error TS2430: Interface 'I6' incorrectly extends interface 'B'.
-  Types of property 'a2' are incompatible.
-    Type 'new <T>(x: T) => string[]' is not assignable to type 'new <T>(x: T) => T[]'.
-      Type 'string[]' is not assignable to type 'T[]'.
-        Type 'string' is not assignable to type 'T'.
-          'string' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+  The types returned by 'new a2(...)' are incompatible between these types.
+    Type 'string[]' is not assignable to type 'T[]'.
+      Type 'string' is not assignable to type 'T'.
+        'string' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/constructSignatureAssignabilityInInheritance3.ts(95,19): error TS2430: Interface 'I7' incorrectly extends interface 'C'.
-  Types of property 'a2' are incompatible.
-    Type 'new <T>(x: T) => T[]' is not assignable to type 'new <T>(x: T) => string[]'.
-      Type 'T[]' is not assignable to type 'string[]'.
-        Type 'T' is not assignable to type 'string'.
+  The types returned by 'new a2(...)' are incompatible between these types.
+    Type 'T[]' is not assignable to type 'string[]'.
+      Type 'T' is not assignable to type 'string'.
 
 
 ==== tests/cases/conformance/types/typeRelationships/assignmentCompatibility/constructSignatureAssignabilityInInheritance3.ts (6 errors) ====
@@ -160,11 +158,10 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/construc
             interface I6 extends B {
                       ~~
 !!! error TS2430: Interface 'I6' incorrectly extends interface 'B'.
-!!! error TS2430:   Types of property 'a2' are incompatible.
-!!! error TS2430:     Type 'new <T>(x: T) => string[]' is not assignable to type 'new <T>(x: T) => T[]'.
-!!! error TS2430:       Type 'string[]' is not assignable to type 'T[]'.
-!!! error TS2430:         Type 'string' is not assignable to type 'T'.
-!!! error TS2430:           'string' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+!!! error TS2430:   The types returned by 'new a2(...)' are incompatible between these types.
+!!! error TS2430:     Type 'string[]' is not assignable to type 'T[]'.
+!!! error TS2430:       Type 'string' is not assignable to type 'T'.
+!!! error TS2430:         'string' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
                 a2: new <T>(x: T) => string[]; // error
             }
     
@@ -176,10 +173,9 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/construc
             interface I7 extends C {
                       ~~
 !!! error TS2430: Interface 'I7' incorrectly extends interface 'C'.
-!!! error TS2430:   Types of property 'a2' are incompatible.
-!!! error TS2430:     Type 'new <T>(x: T) => T[]' is not assignable to type 'new <T>(x: T) => string[]'.
-!!! error TS2430:       Type 'T[]' is not assignable to type 'string[]'.
-!!! error TS2430:         Type 'T' is not assignable to type 'string'.
+!!! error TS2430:   The types returned by 'new a2(...)' are incompatible between these types.
+!!! error TS2430:     Type 'T[]' is not assignable to type 'string[]'.
+!!! error TS2430:       Type 'T' is not assignable to type 'string'.
                 a2: new <T>(x: T) => T[]; // error
             }
     
diff --git a/tests/baselines/reference/covariantCallbacks.errors.txt b/tests/baselines/reference/covariantCallbacks.errors.txt
index 9ee5a9e2fed..401bf454baa 100644
--- a/tests/baselines/reference/covariantCallbacks.errors.txt
+++ b/tests/baselines/reference/covariantCallbacks.errors.txt
@@ -10,9 +10,8 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/covarian
           Type 'A' is not assignable to type 'B'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/covariantCallbacks.ts(43,5): error TS2322: Type 'AList2' is not assignable to type 'BList2'.
   Types of property 'forEach' are incompatible.
-    Type '(cb: (item: A) => boolean) => void' is not assignable to type '(cb: (item: A) => void) => void'.
-      Types of parameters 'cb' and 'cb' are incompatible.
-        Type 'void' is not assignable to type 'boolean'.
+    Types of parameters 'cb' and 'cb' are incompatible.
+      Type 'void' is not assignable to type 'boolean'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/covariantCallbacks.ts(56,5): error TS2322: Type 'AList3' is not assignable to type 'BList3'.
   Types of property 'forEach' are incompatible.
     Type '(cb: (item: A) => void) => void' is not assignable to type '(cb: (item: A, context: any) => void) => void'.
@@ -86,9 +85,8 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/covarian
         ~
 !!! error TS2322: Type 'AList2' is not assignable to type 'BList2'.
 !!! error TS2322:   Types of property 'forEach' are incompatible.
-!!! error TS2322:     Type '(cb: (item: A) => boolean) => void' is not assignable to type '(cb: (item: A) => void) => void'.
-!!! error TS2322:       Types of parameters 'cb' and 'cb' are incompatible.
-!!! error TS2322:         Type 'void' is not assignable to type 'boolean'.
+!!! error TS2322:     Types of parameters 'cb' and 'cb' are incompatible.
+!!! error TS2322:       Type 'void' is not assignable to type 'boolean'.
     }
     
     interface AList3 {
diff --git a/tests/baselines/reference/decoratorCallGeneric.errors.txt b/tests/baselines/reference/decoratorCallGeneric.errors.txt
index c2e4042743e..495160a191b 100644
--- a/tests/baselines/reference/decoratorCallGeneric.errors.txt
+++ b/tests/baselines/reference/decoratorCallGeneric.errors.txt
@@ -1,7 +1,6 @@
 tests/cases/conformance/decorators/decoratorCallGeneric.ts(7,2): error TS2345: Argument of type 'typeof C' is not assignable to parameter of type 'I<C>'.
-  Types of property 'm' are incompatible.
-    Type '() => void' is not assignable to type '() => C'.
-      Type 'void' is not assignable to type 'C'.
+  The types returned by 'm()' are incompatible between these types.
+    Type 'void' is not assignable to type 'C'.
 
 
 ==== tests/cases/conformance/decorators/decoratorCallGeneric.ts (1 errors) ====
@@ -14,9 +13,8 @@ tests/cases/conformance/decorators/decoratorCallGeneric.ts(7,2): error TS2345: A
     @dec
      ~~~
 !!! error TS2345: Argument of type 'typeof C' is not assignable to parameter of type 'I<C>'.
-!!! error TS2345:   Types of property 'm' are incompatible.
-!!! error TS2345:     Type '() => void' is not assignable to type '() => C'.
-!!! error TS2345:       Type 'void' is not assignable to type 'C'.
+!!! error TS2345:   The types returned by 'm()' are incompatible between these types.
+!!! error TS2345:     Type 'void' is not assignable to type 'C'.
     class C {
         _brand: any;
         static m() {}
diff --git a/tests/baselines/reference/deepExcessPropertyCheckingWhenTargetIsIntersection.errors.txt b/tests/baselines/reference/deepExcessPropertyCheckingWhenTargetIsIntersection.errors.txt
index 6a83638ba90..1f2552d47f2 100644
--- a/tests/baselines/reference/deepExcessPropertyCheckingWhenTargetIsIntersection.errors.txt
+++ b/tests/baselines/reference/deepExcessPropertyCheckingWhenTargetIsIntersection.errors.txt
@@ -1,10 +1,8 @@
 tests/cases/compiler/deepExcessPropertyCheckingWhenTargetIsIntersection.ts(21,33): error TS2322: Type '{ INVALID_PROP_NAME: string; ariaLabel: string; }' is not assignable to type 'ITestProps'.
   Object literal may only specify known properties, and 'INVALID_PROP_NAME' does not exist in type 'ITestProps'.
-tests/cases/compiler/deepExcessPropertyCheckingWhenTargetIsIntersection.ts(27,34): error TS2326: Types of property 'icon' are incompatible.
-  Type '{ props: { INVALID_PROP_NAME: string; ariaLabel: string; }; }' is not assignable to type 'NestedProp<ITestProps>'.
-    Types of property 'props' are incompatible.
-      Type '{ INVALID_PROP_NAME: string; ariaLabel: string; }' is not assignable to type 'ITestProps'.
-        Object literal may only specify known properties, and 'INVALID_PROP_NAME' does not exist in type 'ITestProps'.
+tests/cases/compiler/deepExcessPropertyCheckingWhenTargetIsIntersection.ts(27,34): error TS2200: The types of 'icon.props' are incompatible between these types.
+  Type '{ INVALID_PROP_NAME: string; ariaLabel: string; }' is not assignable to type 'ITestProps'.
+    Object literal may only specify known properties, and 'INVALID_PROP_NAME' does not exist in type 'ITestProps'.
 
 
 ==== tests/cases/compiler/deepExcessPropertyCheckingWhenTargetIsIntersection.ts (2 errors) ====
@@ -40,9 +38,7 @@ tests/cases/compiler/deepExcessPropertyCheckingWhenTargetIsIntersection.ts(27,34
     
     TestComponent2({icon: { props: { INVALID_PROP_NAME: 'share', ariaLabel: 'test label' } }});
                                      ~~~~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2326: Types of property 'icon' are incompatible.
-!!! error TS2326:   Type '{ props: { INVALID_PROP_NAME: string; ariaLabel: string; }; }' is not assignable to type 'NestedProp<ITestProps>'.
-!!! error TS2326:     Types of property 'props' are incompatible.
-!!! error TS2326:       Type '{ INVALID_PROP_NAME: string; ariaLabel: string; }' is not assignable to type 'ITestProps'.
-!!! error TS2326:         Object literal may only specify known properties, and 'INVALID_PROP_NAME' does not exist in type 'ITestProps'.
+!!! error TS2200: The types of 'icon.props' are incompatible between these types.
+!!! error TS2200:   Type '{ INVALID_PROP_NAME: string; ariaLabel: string; }' is not assignable to type 'ITestProps'.
+!!! error TS2200:     Object literal may only specify known properties, and 'INVALID_PROP_NAME' does not exist in type 'ITestProps'.
     
\ No newline at end of file
diff --git a/tests/baselines/reference/deeplyNestedAssignabilityErrorsCombined.errors.txt b/tests/baselines/reference/deeplyNestedAssignabilityErrorsCombined.errors.txt
new file mode 100644
index 00000000000..6245d06d2b7
--- /dev/null
+++ b/tests/baselines/reference/deeplyNestedAssignabilityErrorsCombined.errors.txt
@@ -0,0 +1,32 @@
+tests/cases/compiler/deeplyNestedAssignabilityErrorsCombined.ts(3,1): error TS2322: Type '{ a: { b: { c: { d: { e: { f(): { g: number; }; }; }; }; }; }; }' is not assignable to type '{ a: { b: { c: { d: { e: { f(): { g: string; }; }; }; }; }; }; }'.
+  The types of 'a.b.c.d.e.f().g' are incompatible between these types.
+    Type 'number' is not assignable to type 'string'.
+tests/cases/compiler/deeplyNestedAssignabilityErrorsCombined.ts(15,1): error TS2322: Type '{ a: { b: { c: { d: { e: { f: typeof Ctor2; }; }; }; }; }; }' is not assignable to type '{ a: { b: { c: { d: { e: { f: typeof Ctor1; }; }; }; }; }; }'.
+  The types of '(new a.b.c.d.e.f()).g' are incompatible between these types.
+    Type 'number' is not assignable to type 'string'.
+
+
+==== tests/cases/compiler/deeplyNestedAssignabilityErrorsCombined.ts (2 errors) ====
+    let x = { a: { b: { c: { d: { e: { f() { return { g: "hello" }; } } } } } } };
+    let y = { a: { b: { c: { d: { e: { f() { return { g: 12345 }; } } } } } } };
+    x = y;
+    ~
+!!! error TS2322: Type '{ a: { b: { c: { d: { e: { f(): { g: number; }; }; }; }; }; }; }' is not assignable to type '{ a: { b: { c: { d: { e: { f(): { g: string; }; }; }; }; }; }; }'.
+!!! error TS2322:   The types of 'a.b.c.d.e.f().g' are incompatible between these types.
+!!! error TS2322:     Type 'number' is not assignable to type 'string'.
+    
+    class Ctor1 {
+        g = "ok"
+    }
+    
+    class Ctor2 {
+        g = 12;
+    }
+    
+    let x2 = { a: { b: { c: { d: { e: { f: Ctor1 } } } } } };
+    let y2 = { a: { b: { c: { d: { e: { f: Ctor2 } } } } } };
+    x2 = y2;
+    ~~
+!!! error TS2322: Type '{ a: { b: { c: { d: { e: { f: typeof Ctor2; }; }; }; }; }; }' is not assignable to type '{ a: { b: { c: { d: { e: { f: typeof Ctor1; }; }; }; }; }; }'.
+!!! error TS2322:   The types of '(new a.b.c.d.e.f()).g' are incompatible between these types.
+!!! error TS2322:     Type 'number' is not assignable to type 'string'.
\ No newline at end of file
diff --git a/tests/baselines/reference/deeplyNestedAssignabilityErrorsCombined.js b/tests/baselines/reference/deeplyNestedAssignabilityErrorsCombined.js
new file mode 100644
index 00000000000..01bdcc7f253
--- /dev/null
+++ b/tests/baselines/reference/deeplyNestedAssignabilityErrorsCombined.js
@@ -0,0 +1,36 @@
+//// [deeplyNestedAssignabilityErrorsCombined.ts]
+let x = { a: { b: { c: { d: { e: { f() { return { g: "hello" }; } } } } } } };
+let y = { a: { b: { c: { d: { e: { f() { return { g: 12345 }; } } } } } } };
+x = y;
+
+class Ctor1 {
+    g = "ok"
+}
+
+class Ctor2 {
+    g = 12;
+}
+
+let x2 = { a: { b: { c: { d: { e: { f: Ctor1 } } } } } };
+let y2 = { a: { b: { c: { d: { e: { f: Ctor2 } } } } } };
+x2 = y2;
+
+//// [deeplyNestedAssignabilityErrorsCombined.js]
+var x = { a: { b: { c: { d: { e: { f: function () { return { g: "hello" }; } } } } } } };
+var y = { a: { b: { c: { d: { e: { f: function () { return { g: 12345 }; } } } } } } };
+x = y;
+var Ctor1 = /** @class */ (function () {
+    function Ctor1() {
+        this.g = "ok";
+    }
+    return Ctor1;
+}());
+var Ctor2 = /** @class */ (function () {
+    function Ctor2() {
+        this.g = 12;
+    }
+    return Ctor2;
+}());
+var x2 = { a: { b: { c: { d: { e: { f: Ctor1 } } } } } };
+var y2 = { a: { b: { c: { d: { e: { f: Ctor2 } } } } } };
+x2 = y2;
diff --git a/tests/baselines/reference/deeplyNestedAssignabilityErrorsCombined.symbols b/tests/baselines/reference/deeplyNestedAssignabilityErrorsCombined.symbols
new file mode 100644
index 00000000000..12333869923
--- /dev/null
+++ b/tests/baselines/reference/deeplyNestedAssignabilityErrorsCombined.symbols
@@ -0,0 +1,63 @@
+=== tests/cases/compiler/deeplyNestedAssignabilityErrorsCombined.ts ===
+let x = { a: { b: { c: { d: { e: { f() { return { g: "hello" }; } } } } } } };
+>x : Symbol(x, Decl(deeplyNestedAssignabilityErrorsCombined.ts, 0, 3))
+>a : Symbol(a, Decl(deeplyNestedAssignabilityErrorsCombined.ts, 0, 9))
+>b : Symbol(b, Decl(deeplyNestedAssignabilityErrorsCombined.ts, 0, 14))
+>c : Symbol(c, Decl(deeplyNestedAssignabilityErrorsCombined.ts, 0, 19))
+>d : Symbol(d, Decl(deeplyNestedAssignabilityErrorsCombined.ts, 0, 24))
+>e : Symbol(e, Decl(deeplyNestedAssignabilityErrorsCombined.ts, 0, 29))
+>f : Symbol(f, Decl(deeplyNestedAssignabilityErrorsCombined.ts, 0, 34))
+>g : Symbol(g, Decl(deeplyNestedAssignabilityErrorsCombined.ts, 0, 49))
+
+let y = { a: { b: { c: { d: { e: { f() { return { g: 12345 }; } } } } } } };
+>y : Symbol(y, Decl(deeplyNestedAssignabilityErrorsCombined.ts, 1, 3))
+>a : Symbol(a, Decl(deeplyNestedAssignabilityErrorsCombined.ts, 1, 9))
+>b : Symbol(b, Decl(deeplyNestedAssignabilityErrorsCombined.ts, 1, 14))
+>c : Symbol(c, Decl(deeplyNestedAssignabilityErrorsCombined.ts, 1, 19))
+>d : Symbol(d, Decl(deeplyNestedAssignabilityErrorsCombined.ts, 1, 24))
+>e : Symbol(e, Decl(deeplyNestedAssignabilityErrorsCombined.ts, 1, 29))
+>f : Symbol(f, Decl(deeplyNestedAssignabilityErrorsCombined.ts, 1, 34))
+>g : Symbol(g, Decl(deeplyNestedAssignabilityErrorsCombined.ts, 1, 49))
+
+x = y;
+>x : Symbol(x, Decl(deeplyNestedAssignabilityErrorsCombined.ts, 0, 3))
+>y : Symbol(y, Decl(deeplyNestedAssignabilityErrorsCombined.ts, 1, 3))
+
+class Ctor1 {
+>Ctor1 : Symbol(Ctor1, Decl(deeplyNestedAssignabilityErrorsCombined.ts, 2, 6))
+
+    g = "ok"
+>g : Symbol(Ctor1.g, Decl(deeplyNestedAssignabilityErrorsCombined.ts, 4, 13))
+}
+
+class Ctor2 {
+>Ctor2 : Symbol(Ctor2, Decl(deeplyNestedAssignabilityErrorsCombined.ts, 6, 1))
+
+    g = 12;
+>g : Symbol(Ctor2.g, Decl(deeplyNestedAssignabilityErrorsCombined.ts, 8, 13))
+}
+
+let x2 = { a: { b: { c: { d: { e: { f: Ctor1 } } } } } };
+>x2 : Symbol(x2, Decl(deeplyNestedAssignabilityErrorsCombined.ts, 12, 3))
+>a : Symbol(a, Decl(deeplyNestedAssignabilityErrorsCombined.ts, 12, 10))
+>b : Symbol(b, Decl(deeplyNestedAssignabilityErrorsCombined.ts, 12, 15))
+>c : Symbol(c, Decl(deeplyNestedAssignabilityErrorsCombined.ts, 12, 20))
+>d : Symbol(d, Decl(deeplyNestedAssignabilityErrorsCombined.ts, 12, 25))
+>e : Symbol(e, Decl(deeplyNestedAssignabilityErrorsCombined.ts, 12, 30))
+>f : Symbol(f, Decl(deeplyNestedAssignabilityErrorsCombined.ts, 12, 35))
+>Ctor1 : Symbol(Ctor1, Decl(deeplyNestedAssignabilityErrorsCombined.ts, 2, 6))
+
+let y2 = { a: { b: { c: { d: { e: { f: Ctor2 } } } } } };
+>y2 : Symbol(y2, Decl(deeplyNestedAssignabilityErrorsCombined.ts, 13, 3))
+>a : Symbol(a, Decl(deeplyNestedAssignabilityErrorsCombined.ts, 13, 10))
+>b : Symbol(b, Decl(deeplyNestedAssignabilityErrorsCombined.ts, 13, 15))
+>c : Symbol(c, Decl(deeplyNestedAssignabilityErrorsCombined.ts, 13, 20))
+>d : Symbol(d, Decl(deeplyNestedAssignabilityErrorsCombined.ts, 13, 25))
+>e : Symbol(e, Decl(deeplyNestedAssignabilityErrorsCombined.ts, 13, 30))
+>f : Symbol(f, Decl(deeplyNestedAssignabilityErrorsCombined.ts, 13, 35))
+>Ctor2 : Symbol(Ctor2, Decl(deeplyNestedAssignabilityErrorsCombined.ts, 6, 1))
+
+x2 = y2;
+>x2 : Symbol(x2, Decl(deeplyNestedAssignabilityErrorsCombined.ts, 12, 3))
+>y2 : Symbol(y2, Decl(deeplyNestedAssignabilityErrorsCombined.ts, 13, 3))
+
diff --git a/tests/baselines/reference/deeplyNestedAssignabilityErrorsCombined.types b/tests/baselines/reference/deeplyNestedAssignabilityErrorsCombined.types
new file mode 100644
index 00000000000..565de61ef08
--- /dev/null
+++ b/tests/baselines/reference/deeplyNestedAssignabilityErrorsCombined.types
@@ -0,0 +1,95 @@
+=== tests/cases/compiler/deeplyNestedAssignabilityErrorsCombined.ts ===
+let x = { a: { b: { c: { d: { e: { f() { return { g: "hello" }; } } } } } } };
+>x : { a: { b: { c: { d: { e: { f(): { g: string; }; }; }; }; }; }; }
+>{ a: { b: { c: { d: { e: { f() { return { g: "hello" }; } } } } } } } : { a: { b: { c: { d: { e: { f(): { g: string; }; }; }; }; }; }; }
+>a : { b: { c: { d: { e: { f(): { g: string; }; }; }; }; }; }
+>{ b: { c: { d: { e: { f() { return { g: "hello" }; } } } } } } : { b: { c: { d: { e: { f(): { g: string; }; }; }; }; }; }
+>b : { c: { d: { e: { f(): { g: string; }; }; }; }; }
+>{ c: { d: { e: { f() { return { g: "hello" }; } } } } } : { c: { d: { e: { f(): { g: string; }; }; }; }; }
+>c : { d: { e: { f(): { g: string; }; }; }; }
+>{ d: { e: { f() { return { g: "hello" }; } } } } : { d: { e: { f(): { g: string; }; }; }; }
+>d : { e: { f(): { g: string; }; }; }
+>{ e: { f() { return { g: "hello" }; } } } : { e: { f(): { g: string; }; }; }
+>e : { f(): { g: string; }; }
+>{ f() { return { g: "hello" }; } } : { f(): { g: string; }; }
+>f : () => { g: string; }
+>{ g: "hello" } : { g: string; }
+>g : string
+>"hello" : "hello"
+
+let y = { a: { b: { c: { d: { e: { f() { return { g: 12345 }; } } } } } } };
+>y : { a: { b: { c: { d: { e: { f(): { g: number; }; }; }; }; }; }; }
+>{ a: { b: { c: { d: { e: { f() { return { g: 12345 }; } } } } } } } : { a: { b: { c: { d: { e: { f(): { g: number; }; }; }; }; }; }; }
+>a : { b: { c: { d: { e: { f(): { g: number; }; }; }; }; }; }
+>{ b: { c: { d: { e: { f() { return { g: 12345 }; } } } } } } : { b: { c: { d: { e: { f(): { g: number; }; }; }; }; }; }
+>b : { c: { d: { e: { f(): { g: number; }; }; }; }; }
+>{ c: { d: { e: { f() { return { g: 12345 }; } } } } } : { c: { d: { e: { f(): { g: number; }; }; }; }; }
+>c : { d: { e: { f(): { g: number; }; }; }; }
+>{ d: { e: { f() { return { g: 12345 }; } } } } : { d: { e: { f(): { g: number; }; }; }; }
+>d : { e: { f(): { g: number; }; }; }
+>{ e: { f() { return { g: 12345 }; } } } : { e: { f(): { g: number; }; }; }
+>e : { f(): { g: number; }; }
+>{ f() { return { g: 12345 }; } } : { f(): { g: number; }; }
+>f : () => { g: number; }
+>{ g: 12345 } : { g: number; }
+>g : number
+>12345 : 12345
+
+x = y;
+>x = y : { a: { b: { c: { d: { e: { f(): { g: number; }; }; }; }; }; }; }
+>x : { a: { b: { c: { d: { e: { f(): { g: string; }; }; }; }; }; }; }
+>y : { a: { b: { c: { d: { e: { f(): { g: number; }; }; }; }; }; }; }
+
+class Ctor1 {
+>Ctor1 : Ctor1
+
+    g = "ok"
+>g : string
+>"ok" : "ok"
+}
+
+class Ctor2 {
+>Ctor2 : Ctor2
+
+    g = 12;
+>g : number
+>12 : 12
+}
+
+let x2 = { a: { b: { c: { d: { e: { f: Ctor1 } } } } } };
+>x2 : { a: { b: { c: { d: { e: { f: typeof Ctor1; }; }; }; }; }; }
+>{ a: { b: { c: { d: { e: { f: Ctor1 } } } } } } : { a: { b: { c: { d: { e: { f: typeof Ctor1; }; }; }; }; }; }
+>a : { b: { c: { d: { e: { f: typeof Ctor1; }; }; }; }; }
+>{ b: { c: { d: { e: { f: Ctor1 } } } } } : { b: { c: { d: { e: { f: typeof Ctor1; }; }; }; }; }
+>b : { c: { d: { e: { f: typeof Ctor1; }; }; }; }
+>{ c: { d: { e: { f: Ctor1 } } } } : { c: { d: { e: { f: typeof Ctor1; }; }; }; }
+>c : { d: { e: { f: typeof Ctor1; }; }; }
+>{ d: { e: { f: Ctor1 } } } : { d: { e: { f: typeof Ctor1; }; }; }
+>d : { e: { f: typeof Ctor1; }; }
+>{ e: { f: Ctor1 } } : { e: { f: typeof Ctor1; }; }
+>e : { f: typeof Ctor1; }
+>{ f: Ctor1 } : { f: typeof Ctor1; }
+>f : typeof Ctor1
+>Ctor1 : typeof Ctor1
+
+let y2 = { a: { b: { c: { d: { e: { f: Ctor2 } } } } } };
+>y2 : { a: { b: { c: { d: { e: { f: typeof Ctor2; }; }; }; }; }; }
+>{ a: { b: { c: { d: { e: { f: Ctor2 } } } } } } : { a: { b: { c: { d: { e: { f: typeof Ctor2; }; }; }; }; }; }
+>a : { b: { c: { d: { e: { f: typeof Ctor2; }; }; }; }; }
+>{ b: { c: { d: { e: { f: Ctor2 } } } } } : { b: { c: { d: { e: { f: typeof Ctor2; }; }; }; }; }
+>b : { c: { d: { e: { f: typeof Ctor2; }; }; }; }
+>{ c: { d: { e: { f: Ctor2 } } } } : { c: { d: { e: { f: typeof Ctor2; }; }; }; }
+>c : { d: { e: { f: typeof Ctor2; }; }; }
+>{ d: { e: { f: Ctor2 } } } : { d: { e: { f: typeof Ctor2; }; }; }
+>d : { e: { f: typeof Ctor2; }; }
+>{ e: { f: Ctor2 } } : { e: { f: typeof Ctor2; }; }
+>e : { f: typeof Ctor2; }
+>{ f: Ctor2 } : { f: typeof Ctor2; }
+>f : typeof Ctor2
+>Ctor2 : typeof Ctor2
+
+x2 = y2;
+>x2 = y2 : { a: { b: { c: { d: { e: { f: typeof Ctor2; }; }; }; }; }; }
+>x2 : { a: { b: { c: { d: { e: { f: typeof Ctor1; }; }; }; }; }; }
+>y2 : { a: { b: { c: { d: { e: { f: typeof Ctor2; }; }; }; }; }; }
+
diff --git a/tests/baselines/reference/elaboratedErrorsOnNullableTargets01.errors.txt b/tests/baselines/reference/elaboratedErrorsOnNullableTargets01.errors.txt
index dc7e3f10bd1..b84fb863ad8 100644
--- a/tests/baselines/reference/elaboratedErrorsOnNullableTargets01.errors.txt
+++ b/tests/baselines/reference/elaboratedErrorsOnNullableTargets01.errors.txt
@@ -1,9 +1,7 @@
 tests/cases/compiler/elaboratedErrorsOnNullableTargets01.ts(4,1): error TS2322: Type '{ foo: { bar: number | undefined; }; }' is not assignable to type '{ foo: { bar: string | null; } | undefined; }'.
-  Types of property 'foo' are incompatible.
-    Type '{ bar: number | undefined; }' is not assignable to type '{ bar: string | null; }'.
-      Types of property 'bar' are incompatible.
-        Type 'number | undefined' is not assignable to type 'string | null'.
-          Type 'undefined' is not assignable to type 'string | null'.
+  The types of 'foo.bar' are incompatible between these types.
+    Type 'number | undefined' is not assignable to type 'string | null'.
+      Type 'undefined' is not assignable to type 'string | null'.
 tests/cases/compiler/elaboratedErrorsOnNullableTargets01.ts(6,1): error TS2322: Type '{ foo: { bar: string | null; } | undefined; } | null | undefined' is not assignable to type '{ foo: { bar: number | undefined; }; }'.
   Type 'undefined' is not assignable to type '{ foo: { bar: number | undefined; }; }'.
 
@@ -15,11 +13,9 @@ tests/cases/compiler/elaboratedErrorsOnNullableTargets01.ts(6,1): error TS2322:
     x = y;
     ~
 !!! error TS2322: Type '{ foo: { bar: number | undefined; }; }' is not assignable to type '{ foo: { bar: string | null; } | undefined; }'.
-!!! error TS2322:   Types of property 'foo' are incompatible.
-!!! error TS2322:     Type '{ bar: number | undefined; }' is not assignable to type '{ bar: string | null; }'.
-!!! error TS2322:       Types of property 'bar' are incompatible.
-!!! error TS2322:         Type 'number | undefined' is not assignable to type 'string | null'.
-!!! error TS2322:           Type 'undefined' is not assignable to type 'string | null'.
+!!! error TS2322:   The types of 'foo.bar' are incompatible between these types.
+!!! error TS2322:     Type 'number | undefined' is not assignable to type 'string | null'.
+!!! error TS2322:       Type 'undefined' is not assignable to type 'string | null'.
     
     y = x;
     ~
diff --git a/tests/baselines/reference/everyTypeWithAnnotationAndInvalidInitializer.errors.txt b/tests/baselines/reference/everyTypeWithAnnotationAndInvalidInitializer.errors.txt
index 31848458a87..f552bb35ca4 100644
--- a/tests/baselines/reference/everyTypeWithAnnotationAndInvalidInitializer.errors.txt
+++ b/tests/baselines/reference/everyTypeWithAnnotationAndInvalidInitializer.errors.txt
@@ -17,9 +17,8 @@ tests/cases/conformance/statements/VariableStatements/everyTypeWithAnnotationAnd
     Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/statements/VariableStatements/everyTypeWithAnnotationAndInvalidInitializer.ts(48,32): error TS2322: Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/statements/VariableStatements/everyTypeWithAnnotationAndInvalidInitializer.ts(50,5): error TS2322: Type 'typeof N' is not assignable to type 'typeof M'.
-  Types of property 'A' are incompatible.
-    Type 'typeof N.A' is not assignable to type 'typeof M.A'.
-      Property 'name' is missing in type 'N.A' but required in type 'M.A'.
+  The types returned by 'new A()' are incompatible between these types.
+    Property 'name' is missing in type 'N.A' but required in type 'M.A'.
 tests/cases/conformance/statements/VariableStatements/everyTypeWithAnnotationAndInvalidInitializer.ts(51,5): error TS2322: Type 'N.A' is not assignable to type 'M.A'.
 tests/cases/conformance/statements/VariableStatements/everyTypeWithAnnotationAndInvalidInitializer.ts(52,5): error TS2322: Type '(x: number) => boolean' is not assignable to type '(x: number) => string'.
   Type 'boolean' is not assignable to type 'string'.
@@ -112,9 +111,8 @@ tests/cases/conformance/statements/VariableStatements/everyTypeWithAnnotationAnd
     var aModule: typeof M = N;
         ~~~~~~~
 !!! error TS2322: Type 'typeof N' is not assignable to type 'typeof M'.
-!!! error TS2322:   Types of property 'A' are incompatible.
-!!! error TS2322:     Type 'typeof N.A' is not assignable to type 'typeof M.A'.
-!!! error TS2322:       Property 'name' is missing in type 'N.A' but required in type 'M.A'.
+!!! error TS2322:   The types returned by 'new A()' are incompatible between these types.
+!!! error TS2322:     Property 'name' is missing in type 'N.A' but required in type 'M.A'.
 !!! related TS2728 tests/cases/conformance/statements/VariableStatements/everyTypeWithAnnotationAndInvalidInitializer.ts:20:9: 'name' is declared here.
     var aClassInModule: M.A = new N.A();
         ~~~~~~~~~~~~~~
diff --git a/tests/baselines/reference/extendAndImplementTheSameBaseType2.errors.txt b/tests/baselines/reference/extendAndImplementTheSameBaseType2.errors.txt
index 799fc7bb8b0..e23d9ebd282 100644
--- a/tests/baselines/reference/extendAndImplementTheSameBaseType2.errors.txt
+++ b/tests/baselines/reference/extendAndImplementTheSameBaseType2.errors.txt
@@ -1,7 +1,6 @@
 tests/cases/compiler/extendAndImplementTheSameBaseType2.ts(7,7): error TS2720: Class 'D' incorrectly implements class 'C<number>'. Did you mean to extend 'C<number>' and inherit its members as a subclass?
-  Types of property 'bar' are incompatible.
-    Type '() => string' is not assignable to type '() => number'.
-      Type 'string' is not assignable to type 'number'.
+  The types returned by 'bar()' are incompatible between these types.
+    Type 'string' is not assignable to type 'number'.
 tests/cases/compiler/extendAndImplementTheSameBaseType2.ts(12,5): error TS2322: Type 'number' is not assignable to type 'string'.
 tests/cases/compiler/extendAndImplementTheSameBaseType2.ts(16,5): error TS2322: Type 'string' is not assignable to type 'number'.
 
@@ -16,9 +15,8 @@ tests/cases/compiler/extendAndImplementTheSameBaseType2.ts(16,5): error TS2322:
     class D extends C<string> implements C<number> {
           ~
 !!! error TS2720: Class 'D' incorrectly implements class 'C<number>'. Did you mean to extend 'C<number>' and inherit its members as a subclass?
-!!! error TS2720:   Types of property 'bar' are incompatible.
-!!! error TS2720:     Type '() => string' is not assignable to type '() => number'.
-!!! error TS2720:       Type 'string' is not assignable to type 'number'.
+!!! error TS2720:   The types returned by 'bar()' are incompatible between these types.
+!!! error TS2720:     Type 'string' is not assignable to type 'number'.
         baz() { }
     }
     
diff --git a/tests/baselines/reference/for-of39.errors.txt b/tests/baselines/reference/for-of39.errors.txt
index a36c1c28a8c..3ecdc46bcfc 100644
--- a/tests/baselines/reference/for-of39.errors.txt
+++ b/tests/baselines/reference/for-of39.errors.txt
@@ -1,18 +1,14 @@
 tests/cases/conformance/es6/for-ofStatements/for-of39.ts(1,11): error TS2769: No overload matches this call.
   Overload 1 of 3, '(iterable: Iterable<readonly [string, boolean]>): Map<string, boolean>', gave the following error.
     Argument of type '([string, number] | [string, true])[]' is not assignable to parameter of type 'Iterable<readonly [string, boolean]>'.
-      Types of property '[Symbol.iterator]' are incompatible.
-        Type '() => IterableIterator<[string, number] | [string, true]>' is not assignable to type '() => Iterator<readonly [string, boolean], any, undefined>'.
-          Type 'IterableIterator<[string, number] | [string, true]>' is not assignable to type 'Iterator<readonly [string, boolean], any, undefined>'.
-            Types of property 'next' are incompatible.
-              Type '(...args: [] | [undefined]) => IteratorResult<[string, number] | [string, true], any>' is not assignable to type '(...args: [] | [undefined]) => IteratorResult<readonly [string, boolean], any>'.
-                Type 'IteratorResult<[string, number] | [string, true], any>' is not assignable to type 'IteratorResult<readonly [string, boolean], any>'.
-                  Type 'IteratorYieldResult<[string, number] | [string, true]>' is not assignable to type 'IteratorResult<readonly [string, boolean], any>'.
-                    Type 'IteratorYieldResult<[string, number] | [string, true]>' is not assignable to type 'IteratorYieldResult<readonly [string, boolean]>'.
-                      Type '[string, number] | [string, true]' is not assignable to type 'readonly [string, boolean]'.
-                        Type '[string, number]' is not assignable to type 'readonly [string, boolean]'.
-                          Types of property '1' are incompatible.
-                            Type 'number' is not assignable to type 'boolean'.
+      The types returned by '[Symbol.iterator]().next(...)' are incompatible between these types.
+        Type 'IteratorResult<[string, number] | [string, true], any>' is not assignable to type 'IteratorResult<readonly [string, boolean], any>'.
+          Type 'IteratorYieldResult<[string, number] | [string, true]>' is not assignable to type 'IteratorResult<readonly [string, boolean], any>'.
+            Type 'IteratorYieldResult<[string, number] | [string, true]>' is not assignable to type 'IteratorYieldResult<readonly [string, boolean]>'.
+              Type '[string, number] | [string, true]' is not assignable to type 'readonly [string, boolean]'.
+                Type '[string, number]' is not assignable to type 'readonly [string, boolean]'.
+                  Types of property '1' are incompatible.
+                    Type 'number' is not assignable to type 'boolean'.
   Overload 2 of 3, '(entries?: readonly (readonly [string, boolean])[]): Map<string, boolean>', gave the following error.
     Type 'number' is not assignable to type 'boolean'.
 
@@ -23,18 +19,14 @@ tests/cases/conformance/es6/for-ofStatements/for-of39.ts(1,11): error TS2769: No
 !!! error TS2769: No overload matches this call.
 !!! error TS2769:   Overload 1 of 3, '(iterable: Iterable<readonly [string, boolean]>): Map<string, boolean>', gave the following error.
 !!! error TS2769:     Argument of type '([string, number] | [string, true])[]' is not assignable to parameter of type 'Iterable<readonly [string, boolean]>'.
-!!! error TS2769:       Types of property '[Symbol.iterator]' are incompatible.
-!!! error TS2769:         Type '() => IterableIterator<[string, number] | [string, true]>' is not assignable to type '() => Iterator<readonly [string, boolean], any, undefined>'.
-!!! error TS2769:           Type 'IterableIterator<[string, number] | [string, true]>' is not assignable to type 'Iterator<readonly [string, boolean], any, undefined>'.
-!!! error TS2769:             Types of property 'next' are incompatible.
-!!! error TS2769:               Type '(...args: [] | [undefined]) => IteratorResult<[string, number] | [string, true], any>' is not assignable to type '(...args: [] | [undefined]) => IteratorResult<readonly [string, boolean], any>'.
-!!! error TS2769:                 Type 'IteratorResult<[string, number] | [string, true], any>' is not assignable to type 'IteratorResult<readonly [string, boolean], any>'.
-!!! error TS2769:                   Type 'IteratorYieldResult<[string, number] | [string, true]>' is not assignable to type 'IteratorResult<readonly [string, boolean], any>'.
-!!! error TS2769:                     Type 'IteratorYieldResult<[string, number] | [string, true]>' is not assignable to type 'IteratorYieldResult<readonly [string, boolean]>'.
-!!! error TS2769:                       Type '[string, number] | [string, true]' is not assignable to type 'readonly [string, boolean]'.
-!!! error TS2769:                         Type '[string, number]' is not assignable to type 'readonly [string, boolean]'.
-!!! error TS2769:                           Types of property '1' are incompatible.
-!!! error TS2769:                             Type 'number' is not assignable to type 'boolean'.
+!!! error TS2769:       The types returned by '[Symbol.iterator]().next(...)' are incompatible between these types.
+!!! error TS2769:         Type 'IteratorResult<[string, number] | [string, true], any>' is not assignable to type 'IteratorResult<readonly [string, boolean], any>'.
+!!! error TS2769:           Type 'IteratorYieldResult<[string, number] | [string, true]>' is not assignable to type 'IteratorResult<readonly [string, boolean], any>'.
+!!! error TS2769:             Type 'IteratorYieldResult<[string, number] | [string, true]>' is not assignable to type 'IteratorYieldResult<readonly [string, boolean]>'.
+!!! error TS2769:               Type '[string, number] | [string, true]' is not assignable to type 'readonly [string, boolean]'.
+!!! error TS2769:                 Type '[string, number]' is not assignable to type 'readonly [string, boolean]'.
+!!! error TS2769:                   Types of property '1' are incompatible.
+!!! error TS2769:                     Type 'number' is not assignable to type 'boolean'.
 !!! error TS2769:   Overload 2 of 3, '(entries?: readonly (readonly [string, boolean])[]): Map<string, boolean>', gave the following error.
 !!! error TS2769:     Type 'number' is not assignable to type 'boolean'.
     for (var [k, v] of map) {
diff --git a/tests/baselines/reference/generatorTypeCheck25.errors.txt b/tests/baselines/reference/generatorTypeCheck25.errors.txt
index 365a19dfdd7..e37f1304963 100644
--- a/tests/baselines/reference/generatorTypeCheck25.errors.txt
+++ b/tests/baselines/reference/generatorTypeCheck25.errors.txt
@@ -1,15 +1,11 @@
 tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck25.ts(4,5): error TS2322: Type '() => Generator<Bar | Baz, void, undefined>' is not assignable to type '() => Iterable<Foo>'.
-  Type 'Generator<Bar | Baz, void, undefined>' is not assignable to type 'Iterable<Foo>'.
-    Types of property '[Symbol.iterator]' are incompatible.
-      Type '() => Generator<Bar | Baz, void, undefined>' is not assignable to type '() => Iterator<Foo, any, undefined>'.
-        Type 'Generator<Bar | Baz, void, undefined>' is not assignable to type 'Iterator<Foo, any, undefined>'.
-          Types of property 'next' are incompatible.
-            Type '(...args: [] | [undefined]) => IteratorResult<Bar | Baz, void>' is not assignable to type '(...args: [] | [undefined]) => IteratorResult<Foo, any>'.
-              Type 'IteratorResult<Bar | Baz, void>' is not assignable to type 'IteratorResult<Foo, any>'.
-                Type 'IteratorYieldResult<Bar | Baz>' is not assignable to type 'IteratorResult<Foo, any>'.
-                  Type 'IteratorYieldResult<Bar | Baz>' is not assignable to type 'IteratorYieldResult<Foo>'.
-                    Type 'Bar | Baz' is not assignable to type 'Foo'.
-                      Property 'x' is missing in type 'Baz' but required in type 'Foo'.
+  Call signature return types 'Generator<Bar | Baz, void, undefined>' and 'Iterable<Foo>' are incompatible.
+    The types returned by '[Symbol.iterator]().next(...)' are incompatible between these types.
+      Type 'IteratorResult<Bar | Baz, void>' is not assignable to type 'IteratorResult<Foo, any>'.
+        Type 'IteratorYieldResult<Bar | Baz>' is not assignable to type 'IteratorResult<Foo, any>'.
+          Type 'IteratorYieldResult<Bar | Baz>' is not assignable to type 'IteratorYieldResult<Foo>'.
+            Type 'Bar | Baz' is not assignable to type 'Foo'.
+              Property 'x' is missing in type 'Baz' but required in type 'Foo'.
 
 
 ==== tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck25.ts (1 errors) ====
@@ -19,17 +15,13 @@ tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck25.ts(4,5): error
     var g3: () => Iterable<Foo> = function* () {
         ~~
 !!! error TS2322: Type '() => Generator<Bar | Baz, void, undefined>' is not assignable to type '() => Iterable<Foo>'.
-!!! error TS2322:   Type 'Generator<Bar | Baz, void, undefined>' is not assignable to type 'Iterable<Foo>'.
-!!! error TS2322:     Types of property '[Symbol.iterator]' are incompatible.
-!!! error TS2322:       Type '() => Generator<Bar | Baz, void, undefined>' is not assignable to type '() => Iterator<Foo, any, undefined>'.
-!!! error TS2322:         Type 'Generator<Bar | Baz, void, undefined>' is not assignable to type 'Iterator<Foo, any, undefined>'.
-!!! error TS2322:           Types of property 'next' are incompatible.
-!!! error TS2322:             Type '(...args: [] | [undefined]) => IteratorResult<Bar | Baz, void>' is not assignable to type '(...args: [] | [undefined]) => IteratorResult<Foo, any>'.
-!!! error TS2322:               Type 'IteratorResult<Bar | Baz, void>' is not assignable to type 'IteratorResult<Foo, any>'.
-!!! error TS2322:                 Type 'IteratorYieldResult<Bar | Baz>' is not assignable to type 'IteratorResult<Foo, any>'.
-!!! error TS2322:                   Type 'IteratorYieldResult<Bar | Baz>' is not assignable to type 'IteratorYieldResult<Foo>'.
-!!! error TS2322:                     Type 'Bar | Baz' is not assignable to type 'Foo'.
-!!! error TS2322:                       Property 'x' is missing in type 'Baz' but required in type 'Foo'.
+!!! error TS2322:   Call signature return types 'Generator<Bar | Baz, void, undefined>' and 'Iterable<Foo>' are incompatible.
+!!! error TS2322:     The types returned by '[Symbol.iterator]().next(...)' are incompatible between these types.
+!!! error TS2322:       Type 'IteratorResult<Bar | Baz, void>' is not assignable to type 'IteratorResult<Foo, any>'.
+!!! error TS2322:         Type 'IteratorYieldResult<Bar | Baz>' is not assignable to type 'IteratorResult<Foo, any>'.
+!!! error TS2322:           Type 'IteratorYieldResult<Bar | Baz>' is not assignable to type 'IteratorYieldResult<Foo>'.
+!!! error TS2322:             Type 'Bar | Baz' is not assignable to type 'Foo'.
+!!! error TS2322:               Property 'x' is missing in type 'Baz' but required in type 'Foo'.
 !!! related TS2728 tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck25.ts:1:13: 'x' is declared here.
         yield;
         yield new Bar;
diff --git a/tests/baselines/reference/generatorTypeCheck63.errors.txt b/tests/baselines/reference/generatorTypeCheck63.errors.txt
index 60dfb089822..10cafbe0ced 100644
--- a/tests/baselines/reference/generatorTypeCheck63.errors.txt
+++ b/tests/baselines/reference/generatorTypeCheck63.errors.txt
@@ -1,11 +1,10 @@
 tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck63.ts(24,61): error TS2345: Argument of type '(state: State) => Generator<number, State, undefined>' is not assignable to parameter of type '(a: State) => IterableIterator<State>'.
-  Type 'Generator<number, State, undefined>' is not assignable to type 'IterableIterator<State>'.
-    Types of property 'next' are incompatible.
-      Type '(...args: [] | [undefined]) => IteratorResult<number, State>' is not assignable to type '(...args: [] | [undefined]) => IteratorResult<State, any>'.
-        Type 'IteratorResult<number, State>' is not assignable to type 'IteratorResult<State, any>'.
-          Type 'IteratorYieldResult<number>' is not assignable to type 'IteratorResult<State, any>'.
-            Type 'IteratorYieldResult<number>' is not assignable to type 'IteratorYieldResult<State>'.
-              Type 'number' is not assignable to type 'State'.
+  Call signature return types 'Generator<number, State, undefined>' and 'IterableIterator<State>' are incompatible.
+    The types returned by 'next(...)' are incompatible between these types.
+      Type 'IteratorResult<number, State>' is not assignable to type 'IteratorResult<State, any>'.
+        Type 'IteratorYieldResult<number>' is not assignable to type 'IteratorResult<State, any>'.
+          Type 'IteratorYieldResult<number>' is not assignable to type 'IteratorYieldResult<State>'.
+            Type 'number' is not assignable to type 'State'.
 
 
 ==== tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck63.ts (1 errors) ====
@@ -35,13 +34,12 @@ tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck63.ts(24,61): err
     export const Nothing: Strategy<State> = strategy("Nothing", function* (state: State) {
                                                                 ~~~~~~~~
 !!! error TS2345: Argument of type '(state: State) => Generator<number, State, undefined>' is not assignable to parameter of type '(a: State) => IterableIterator<State>'.
-!!! error TS2345:   Type 'Generator<number, State, undefined>' is not assignable to type 'IterableIterator<State>'.
-!!! error TS2345:     Types of property 'next' are incompatible.
-!!! error TS2345:       Type '(...args: [] | [undefined]) => IteratorResult<number, State>' is not assignable to type '(...args: [] | [undefined]) => IteratorResult<State, any>'.
-!!! error TS2345:         Type 'IteratorResult<number, State>' is not assignable to type 'IteratorResult<State, any>'.
-!!! error TS2345:           Type 'IteratorYieldResult<number>' is not assignable to type 'IteratorResult<State, any>'.
-!!! error TS2345:             Type 'IteratorYieldResult<number>' is not assignable to type 'IteratorYieldResult<State>'.
-!!! error TS2345:               Type 'number' is not assignable to type 'State'.
+!!! error TS2345:   Call signature return types 'Generator<number, State, undefined>' and 'IterableIterator<State>' are incompatible.
+!!! error TS2345:     The types returned by 'next(...)' are incompatible between these types.
+!!! error TS2345:       Type 'IteratorResult<number, State>' is not assignable to type 'IteratorResult<State, any>'.
+!!! error TS2345:         Type 'IteratorYieldResult<number>' is not assignable to type 'IteratorResult<State, any>'.
+!!! error TS2345:           Type 'IteratorYieldResult<number>' is not assignable to type 'IteratorYieldResult<State>'.
+!!! error TS2345:             Type 'number' is not assignable to type 'State'.
         yield 1;
         return state;
     });
diff --git a/tests/baselines/reference/generatorTypeCheck8.errors.txt b/tests/baselines/reference/generatorTypeCheck8.errors.txt
index 6261d419ddd..ca0b1e30366 100644
--- a/tests/baselines/reference/generatorTypeCheck8.errors.txt
+++ b/tests/baselines/reference/generatorTypeCheck8.errors.txt
@@ -1,10 +1,9 @@
 tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck8.ts(2,17): error TS2322: Type 'Generator<string, any, undefined>' is not assignable to type 'BadGenerator'.
-  Types of property 'next' are incompatible.
-    Type '(...args: [] | [undefined]) => IteratorResult<string, any>' is not assignable to type '(...args: [] | [undefined]) => IteratorResult<number, any>'.
-      Type 'IteratorResult<string, any>' is not assignable to type 'IteratorResult<number, any>'.
-        Type 'IteratorYieldResult<string>' is not assignable to type 'IteratorResult<number, any>'.
-          Type 'IteratorYieldResult<string>' is not assignable to type 'IteratorYieldResult<number>'.
-            Type 'string' is not assignable to type 'number'.
+  The types returned by 'next(...)' are incompatible between these types.
+    Type 'IteratorResult<string, any>' is not assignable to type 'IteratorResult<number, any>'.
+      Type 'IteratorYieldResult<string>' is not assignable to type 'IteratorResult<number, any>'.
+        Type 'IteratorYieldResult<string>' is not assignable to type 'IteratorYieldResult<number>'.
+          Type 'string' is not assignable to type 'number'.
 
 
 ==== tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck8.ts (1 errors) ====
@@ -12,9 +11,8 @@ tests/cases/conformance/es6/yieldExpressions/generatorTypeCheck8.ts(2,17): error
     function* g3(): BadGenerator { }
                     ~~~~~~~~~~~~
 !!! error TS2322: Type 'Generator<string, any, undefined>' is not assignable to type 'BadGenerator'.
-!!! error TS2322:   Types of property 'next' are incompatible.
-!!! error TS2322:     Type '(...args: [] | [undefined]) => IteratorResult<string, any>' is not assignable to type '(...args: [] | [undefined]) => IteratorResult<number, any>'.
-!!! error TS2322:       Type 'IteratorResult<string, any>' is not assignable to type 'IteratorResult<number, any>'.
-!!! error TS2322:         Type 'IteratorYieldResult<string>' is not assignable to type 'IteratorResult<number, any>'.
-!!! error TS2322:           Type 'IteratorYieldResult<string>' is not assignable to type 'IteratorYieldResult<number>'.
-!!! error TS2322:             Type 'string' is not assignable to type 'number'.
\ No newline at end of file
+!!! error TS2322:   The types returned by 'next(...)' are incompatible between these types.
+!!! error TS2322:     Type 'IteratorResult<string, any>' is not assignable to type 'IteratorResult<number, any>'.
+!!! error TS2322:       Type 'IteratorYieldResult<string>' is not assignable to type 'IteratorResult<number, any>'.
+!!! error TS2322:         Type 'IteratorYieldResult<string>' is not assignable to type 'IteratorYieldResult<number>'.
+!!! error TS2322:           Type 'string' is not assignable to type 'number'.
\ No newline at end of file
diff --git a/tests/baselines/reference/generics4.errors.txt b/tests/baselines/reference/generics4.errors.txt
index 06bfa122901..6181685983e 100644
--- a/tests/baselines/reference/generics4.errors.txt
+++ b/tests/baselines/reference/generics4.errors.txt
@@ -1,8 +1,7 @@
 tests/cases/compiler/generics4.ts(7,1): error TS2322: Type 'C<Y>' is not assignable to type 'C<X>'.
   Type 'Y' is not assignable to type 'X'.
-    Types of property 'f' are incompatible.
-      Type '() => boolean' is not assignable to type '() => string'.
-        Type 'boolean' is not assignable to type 'string'.
+    The types returned by 'f()' are incompatible between these types.
+      Type 'boolean' is not assignable to type 'string'.
 
 
 ==== tests/cases/compiler/generics4.ts (1 errors) ====
@@ -16,6 +15,5 @@ tests/cases/compiler/generics4.ts(7,1): error TS2322: Type 'C<Y>' is not assigna
     ~
 !!! error TS2322: Type 'C<Y>' is not assignable to type 'C<X>'.
 !!! error TS2322:   Type 'Y' is not assignable to type 'X'.
-!!! error TS2322:     Types of property 'f' are incompatible.
-!!! error TS2322:       Type '() => boolean' is not assignable to type '() => string'.
-!!! error TS2322:         Type 'boolean' is not assignable to type 'string'.
\ No newline at end of file
+!!! error TS2322:     The types returned by 'f()' are incompatible between these types.
+!!! error TS2322:       Type 'boolean' is not assignable to type 'string'.
\ No newline at end of file
diff --git a/tests/baselines/reference/incompatibleTypes.errors.txt b/tests/baselines/reference/incompatibleTypes.errors.txt
index 0b5e587ad53..66d94bea79c 100644
--- a/tests/baselines/reference/incompatibleTypes.errors.txt
+++ b/tests/baselines/reference/incompatibleTypes.errors.txt
@@ -12,14 +12,12 @@ tests/cases/compiler/incompatibleTypes.ts(34,12): error TS2416: Property 'p1' in
 tests/cases/compiler/incompatibleTypes.ts(42,5): error TS2769: No overload matches this call.
   Overload 1 of 2, '(i: IFoo1): void', gave the following error.
     Argument of type 'C1' is not assignable to parameter of type 'IFoo1'.
-      Types of property 'p1' are incompatible.
-        Type '() => string' is not assignable to type '() => number'.
-          Type 'string' is not assignable to type 'number'.
+      The types returned by 'p1()' are incompatible between these types.
+        Type 'string' is not assignable to type 'number'.
   Overload 2 of 2, '(i: IFoo2): void', gave the following error.
     Argument of type 'C1' is not assignable to parameter of type 'IFoo2'.
-      Types of property 'p1' are incompatible.
-        Type '() => string' is not assignable to type '(s: string) => number'.
-          Type 'string' is not assignable to type 'number'.
+      The types returned by 'p1(...)' are incompatible between these types.
+        Type 'string' is not assignable to type 'number'.
 tests/cases/compiler/incompatibleTypes.ts(49,7): error TS2769: No overload matches this call.
   Overload 1 of 2, '(n: { a: { a: string; }; b: string; }): number', gave the following error.
     Argument of type '{ e: number; f: number; }' is not assignable to parameter of type '{ a: { a: string; }; b: string; }'.
@@ -95,14 +93,12 @@ tests/cases/compiler/incompatibleTypes.ts(74,5): error TS2322: Type '(a: any) =>
 !!! error TS2769: No overload matches this call.
 !!! error TS2769:   Overload 1 of 2, '(i: IFoo1): void', gave the following error.
 !!! error TS2769:     Argument of type 'C1' is not assignable to parameter of type 'IFoo1'.
-!!! error TS2769:       Types of property 'p1' are incompatible.
-!!! error TS2769:         Type '() => string' is not assignable to type '() => number'.
-!!! error TS2769:           Type 'string' is not assignable to type 'number'.
+!!! error TS2769:       The types returned by 'p1()' are incompatible between these types.
+!!! error TS2769:         Type 'string' is not assignable to type 'number'.
 !!! error TS2769:   Overload 2 of 2, '(i: IFoo2): void', gave the following error.
 !!! error TS2769:     Argument of type 'C1' is not assignable to parameter of type 'IFoo2'.
-!!! error TS2769:       Types of property 'p1' are incompatible.
-!!! error TS2769:         Type '() => string' is not assignable to type '(s: string) => number'.
-!!! error TS2769:           Type 'string' is not assignable to type 'number'.
+!!! error TS2769:       The types returned by 'p1(...)' are incompatible between these types.
+!!! error TS2769:         Type 'string' is not assignable to type 'number'.
     
     
     function of1(n: { a: { a: string; }; b: string; }): number;
diff --git a/tests/baselines/reference/inheritedModuleMembersForClodule.errors.txt b/tests/baselines/reference/inheritedModuleMembersForClodule.errors.txt
index 0b7e00d95ce..e2b744d5a25 100644
--- a/tests/baselines/reference/inheritedModuleMembersForClodule.errors.txt
+++ b/tests/baselines/reference/inheritedModuleMembersForClodule.errors.txt
@@ -1,7 +1,6 @@
 tests/cases/compiler/inheritedModuleMembersForClodule.ts(7,7): error TS2417: Class static side 'typeof D' incorrectly extends base class static side 'typeof C'.
-  Types of property 'foo' are incompatible.
-    Type '() => number' is not assignable to type '() => string'.
-      Type 'number' is not assignable to type 'string'.
+  The types returned by 'foo()' are incompatible between these types.
+    Type 'number' is not assignable to type 'string'.
 
 
 ==== tests/cases/compiler/inheritedModuleMembersForClodule.ts (1 errors) ====
@@ -14,9 +13,8 @@ tests/cases/compiler/inheritedModuleMembersForClodule.ts(7,7): error TS2417: Cla
     class D extends C {
           ~
 !!! error TS2417: Class static side 'typeof D' incorrectly extends base class static side 'typeof C'.
-!!! error TS2417:   Types of property 'foo' are incompatible.
-!!! error TS2417:     Type '() => number' is not assignable to type '() => string'.
-!!! error TS2417:       Type 'number' is not assignable to type 'string'.
+!!! error TS2417:   The types returned by 'foo()' are incompatible between these types.
+!!! error TS2417:     Type 'number' is not assignable to type 'string'.
     }
     
     module D {
diff --git a/tests/baselines/reference/interfaceThatHidesBaseProperty2.errors.txt b/tests/baselines/reference/interfaceThatHidesBaseProperty2.errors.txt
index f66e13c0d9d..779a160c5a6 100644
--- a/tests/baselines/reference/interfaceThatHidesBaseProperty2.errors.txt
+++ b/tests/baselines/reference/interfaceThatHidesBaseProperty2.errors.txt
@@ -1,8 +1,6 @@
 tests/cases/conformance/interfaces/interfaceDeclarations/interfaceThatHidesBaseProperty2.ts(5,11): error TS2430: Interface 'Derived' incorrectly extends interface 'Base'.
-  Types of property 'x' are incompatible.
-    Type '{ a: string; }' is not assignable to type '{ a: number; }'.
-      Types of property 'a' are incompatible.
-        Type 'string' is not assignable to type 'number'.
+  The types of 'x.a' are incompatible between these types.
+    Type 'string' is not assignable to type 'number'.
 
 
 ==== tests/cases/conformance/interfaces/interfaceDeclarations/interfaceThatHidesBaseProperty2.ts (1 errors) ====
@@ -13,10 +11,8 @@ tests/cases/conformance/interfaces/interfaceDeclarations/interfaceThatHidesBaseP
     interface Derived extends Base { // error
               ~~~~~~~
 !!! error TS2430: Interface 'Derived' incorrectly extends interface 'Base'.
-!!! error TS2430:   Types of property 'x' are incompatible.
-!!! error TS2430:     Type '{ a: string; }' is not assignable to type '{ a: number; }'.
-!!! error TS2430:       Types of property 'a' are incompatible.
-!!! error TS2430:         Type 'string' is not assignable to type 'number'.
+!!! error TS2430:   The types of 'x.a' are incompatible between these types.
+!!! error TS2430:     Type 'string' is not assignable to type 'number'.
         x: {
             a: string;
         };
diff --git a/tests/baselines/reference/interfaceWithMultipleBaseTypes.errors.txt b/tests/baselines/reference/interfaceWithMultipleBaseTypes.errors.txt
index 138f3d92096..c885a7859d4 100644
--- a/tests/baselines/reference/interfaceWithMultipleBaseTypes.errors.txt
+++ b/tests/baselines/reference/interfaceWithMultipleBaseTypes.errors.txt
@@ -1,20 +1,14 @@
 tests/cases/conformance/interfaces/interfaceDeclarations/interfaceWithMultipleBaseTypes.ts(21,11): error TS2430: Interface 'Derived2' incorrectly extends interface 'Base2'.
-  Types of property 'x' are incompatible.
-    Type '{ a: string; b: number; }' is not assignable to type '{ b: string; }'.
-      Types of property 'b' are incompatible.
-        Type 'number' is not assignable to type 'string'.
+  The types of 'x.b' are incompatible between these types.
+    Type 'number' is not assignable to type 'string'.
 tests/cases/conformance/interfaces/interfaceDeclarations/interfaceWithMultipleBaseTypes.ts(52,15): error TS2320: Interface 'Derived3<T>' cannot simultaneously extend types 'Base1<number>' and 'Base2<number>'.
   Named property 'x' of types 'Base1<number>' and 'Base2<number>' are not identical.
 tests/cases/conformance/interfaces/interfaceDeclarations/interfaceWithMultipleBaseTypes.ts(54,15): error TS2430: Interface 'Derived4<T>' incorrectly extends interface 'Base1<number>'.
-  Types of property 'x' are incompatible.
-    Type '{ a: T; b: T; }' is not assignable to type '{ a: number; }'.
-      Types of property 'a' are incompatible.
-        Type 'T' is not assignable to type 'number'.
+  The types of 'x.a' are incompatible between these types.
+    Type 'T' is not assignable to type 'number'.
 tests/cases/conformance/interfaces/interfaceDeclarations/interfaceWithMultipleBaseTypes.ts(54,15): error TS2430: Interface 'Derived4<T>' incorrectly extends interface 'Base2<number>'.
-  Types of property 'x' are incompatible.
-    Type '{ a: T; b: T; }' is not assignable to type '{ b: number; }'.
-      Types of property 'b' are incompatible.
-        Type 'T' is not assignable to type 'number'.
+  The types of 'x.b' are incompatible between these types.
+    Type 'T' is not assignable to type 'number'.
 tests/cases/conformance/interfaces/interfaceDeclarations/interfaceWithMultipleBaseTypes.ts(60,15): error TS2430: Interface 'Derived5<T>' incorrectly extends interface 'Base1<T>'.
   Types of property 'x' are incompatible.
     Type 'T' is not assignable to type '{ a: T; }'.
@@ -47,10 +41,8 @@ tests/cases/conformance/interfaces/interfaceDeclarations/interfaceWithMultipleBa
     interface Derived2 extends Base1, Base2 { // error
               ~~~~~~~~
 !!! error TS2430: Interface 'Derived2' incorrectly extends interface 'Base2'.
-!!! error TS2430:   Types of property 'x' are incompatible.
-!!! error TS2430:     Type '{ a: string; b: number; }' is not assignable to type '{ b: string; }'.
-!!! error TS2430:       Types of property 'b' are incompatible.
-!!! error TS2430:         Type 'number' is not assignable to type 'string'.
+!!! error TS2430:   The types of 'x.b' are incompatible between these types.
+!!! error TS2430:     Type 'number' is not assignable to type 'string'.
         x: {
             a: string; b: number;
         }
@@ -89,16 +81,12 @@ tests/cases/conformance/interfaces/interfaceDeclarations/interfaceWithMultipleBa
         interface Derived4<T> extends Base1<number>, Base2<number> { // error
                   ~~~~~~~~
 !!! error TS2430: Interface 'Derived4<T>' incorrectly extends interface 'Base1<number>'.
-!!! error TS2430:   Types of property 'x' are incompatible.
-!!! error TS2430:     Type '{ a: T; b: T; }' is not assignable to type '{ a: number; }'.
-!!! error TS2430:       Types of property 'a' are incompatible.
-!!! error TS2430:         Type 'T' is not assignable to type 'number'.
+!!! error TS2430:   The types of 'x.a' are incompatible between these types.
+!!! error TS2430:     Type 'T' is not assignable to type 'number'.
                   ~~~~~~~~
 !!! error TS2430: Interface 'Derived4<T>' incorrectly extends interface 'Base2<number>'.
-!!! error TS2430:   Types of property 'x' are incompatible.
-!!! error TS2430:     Type '{ a: T; b: T; }' is not assignable to type '{ b: number; }'.
-!!! error TS2430:       Types of property 'b' are incompatible.
-!!! error TS2430:         Type 'T' is not assignable to type 'number'.
+!!! error TS2430:   The types of 'x.b' are incompatible between these types.
+!!! error TS2430:     Type 'T' is not assignable to type 'number'.
             x: {
                 a: T; b: T;
             }
diff --git a/tests/baselines/reference/interfaceWithMultipleBaseTypes2.errors.txt b/tests/baselines/reference/interfaceWithMultipleBaseTypes2.errors.txt
index b3459233923..9b7b2eff8ec 100644
--- a/tests/baselines/reference/interfaceWithMultipleBaseTypes2.errors.txt
+++ b/tests/baselines/reference/interfaceWithMultipleBaseTypes2.errors.txt
@@ -1,8 +1,6 @@
 tests/cases/conformance/interfaces/interfaceDeclarations/interfaceWithMultipleBaseTypes2.ts(17,11): error TS2430: Interface 'Derived2' incorrectly extends interface 'Base'.
-  Types of property 'x' are incompatible.
-    Type '{ a: number; b: string; }' is not assignable to type '{ a?: string; b: string; }'.
-      Types of property 'a' are incompatible.
-        Type 'number' is not assignable to type 'string'.
+  The types of 'x.a' are incompatible between these types.
+    Type 'number' is not assignable to type 'string'.
 
 
 ==== tests/cases/conformance/interfaces/interfaceDeclarations/interfaceWithMultipleBaseTypes2.ts (1 errors) ====
@@ -25,10 +23,8 @@ tests/cases/conformance/interfaces/interfaceDeclarations/interfaceWithMultipleBa
     interface Derived2 extends Base, Base2 { // error
               ~~~~~~~~
 !!! error TS2430: Interface 'Derived2' incorrectly extends interface 'Base'.
-!!! error TS2430:   Types of property 'x' are incompatible.
-!!! error TS2430:     Type '{ a: number; b: string; }' is not assignable to type '{ a?: string; b: string; }'.
-!!! error TS2430:       Types of property 'a' are incompatible.
-!!! error TS2430:         Type 'number' is not assignable to type 'string'.
+!!! error TS2430:   The types of 'x.a' are incompatible between these types.
+!!! error TS2430:     Type 'number' is not assignable to type 'string'.
         x: { a: number; b: string }
     }
     
diff --git a/tests/baselines/reference/invariantGenericErrorElaboration.errors.txt b/tests/baselines/reference/invariantGenericErrorElaboration.errors.txt
index 0bd79bcf11d..7ab83c61bcd 100644
--- a/tests/baselines/reference/invariantGenericErrorElaboration.errors.txt
+++ b/tests/baselines/reference/invariantGenericErrorElaboration.errors.txt
@@ -1,13 +1,7 @@
 tests/cases/compiler/invariantGenericErrorElaboration.ts(3,7): error TS2322: Type 'Num' is not assignable to type 'Runtype<any>'.
-  Types of property 'constraint' are incompatible.
-    Type 'Constraint<Num>' is not assignable to type 'Constraint<Runtype<any>>'.
-      Types of property 'constraint' are incompatible.
-        Type 'Constraint<Constraint<Num>>' is not assignable to type 'Constraint<Constraint<Runtype<any>>>'.
-          Types of property 'constraint' are incompatible.
-            Type 'Constraint<Constraint<Constraint<Num>>>' is not assignable to type 'Constraint<Constraint<Constraint<Runtype<any>>>>'.
-              Type 'Constraint<Constraint<Runtype<any>>>' is not assignable to type 'Constraint<Constraint<Num>>'.
-                Types of property 'underlying' are incompatible.
-                  Type 'Constraint<Runtype<any>>' is not assignable to type 'Constraint<Num>'.
+  The types of 'constraint.constraint.constraint' are incompatible between these types.
+    Type 'Constraint<Constraint<Constraint<Num>>>' is not assignable to type 'Constraint<Constraint<Constraint<Runtype<any>>>>'.
+      Type 'Constraint<Runtype<any>>' is not assignable to type 'Constraint<Num>'.
 tests/cases/compiler/invariantGenericErrorElaboration.ts(4,19): error TS2322: Type 'Num' is not assignable to type 'Runtype<any>'.
 
 
@@ -17,16 +11,9 @@ tests/cases/compiler/invariantGenericErrorElaboration.ts(4,19): error TS2322: Ty
     const wat: Runtype<any> = Num;
           ~~~
 !!! error TS2322: Type 'Num' is not assignable to type 'Runtype<any>'.
-!!! error TS2322:   Types of property 'constraint' are incompatible.
-!!! error TS2322:     Type 'Constraint<Num>' is not assignable to type 'Constraint<Runtype<any>>'.
-!!! error TS2322:       Types of property 'constraint' are incompatible.
-!!! error TS2322:         Type 'Constraint<Constraint<Num>>' is not assignable to type 'Constraint<Constraint<Runtype<any>>>'.
-!!! error TS2322:           Types of property 'constraint' are incompatible.
-!!! error TS2322:             Type 'Constraint<Constraint<Constraint<Num>>>' is not assignable to type 'Constraint<Constraint<Constraint<Runtype<any>>>>'.
-!!! error TS2322:               Type 'Constraint<Constraint<Runtype<any>>>' is not assignable to type 'Constraint<Constraint<Num>>'.
-!!! error TS2322:                 Types of property 'underlying' are incompatible.
-!!! error TS2322:                   Type 'Constraint<Runtype<any>>' is not assignable to type 'Constraint<Num>'.
-!!! related TS2728 tests/cases/compiler/invariantGenericErrorElaboration.ts:12:3: 'tag' is declared here.
+!!! error TS2322:   The types of 'constraint.constraint.constraint' are incompatible between these types.
+!!! error TS2322:     Type 'Constraint<Constraint<Constraint<Num>>>' is not assignable to type 'Constraint<Constraint<Constraint<Runtype<any>>>>'.
+!!! error TS2322:       Type 'Constraint<Runtype<any>>' is not assignable to type 'Constraint<Num>'.
     const Foo = Obj({ foo: Num })
                       ~~~
 !!! error TS2322: Type 'Num' is not assignable to type 'Runtype<any>'.
diff --git a/tests/baselines/reference/iterableArrayPattern28.errors.txt b/tests/baselines/reference/iterableArrayPattern28.errors.txt
index 7a1ff6cf42c..605c6feb405 100644
--- a/tests/baselines/reference/iterableArrayPattern28.errors.txt
+++ b/tests/baselines/reference/iterableArrayPattern28.errors.txt
@@ -1,18 +1,14 @@
 tests/cases/conformance/es6/destructuring/iterableArrayPattern28.ts(2,24): error TS2769: No overload matches this call.
   Overload 1 of 3, '(iterable: Iterable<readonly [string, number]>): Map<string, number>', gave the following error.
     Argument of type '([string, number] | [string, boolean])[]' is not assignable to parameter of type 'Iterable<readonly [string, number]>'.
-      Types of property '[Symbol.iterator]' are incompatible.
-        Type '() => IterableIterator<[string, number] | [string, boolean]>' is not assignable to type '() => Iterator<readonly [string, number], any, undefined>'.
-          Type 'IterableIterator<[string, number] | [string, boolean]>' is not assignable to type 'Iterator<readonly [string, number], any, undefined>'.
-            Types of property 'next' are incompatible.
-              Type '(...args: [] | [undefined]) => IteratorResult<[string, number] | [string, boolean], any>' is not assignable to type '(...args: [] | [undefined]) => IteratorResult<readonly [string, number], any>'.
-                Type 'IteratorResult<[string, number] | [string, boolean], any>' is not assignable to type 'IteratorResult<readonly [string, number], any>'.
-                  Type 'IteratorYieldResult<[string, number] | [string, boolean]>' is not assignable to type 'IteratorResult<readonly [string, number], any>'.
-                    Type 'IteratorYieldResult<[string, number] | [string, boolean]>' is not assignable to type 'IteratorYieldResult<readonly [string, number]>'.
-                      Type '[string, number] | [string, boolean]' is not assignable to type 'readonly [string, number]'.
-                        Type '[string, boolean]' is not assignable to type 'readonly [string, number]'.
-                          Types of property '1' are incompatible.
-                            Type 'boolean' is not assignable to type 'number'.
+      The types returned by '[Symbol.iterator]().next(...)' are incompatible between these types.
+        Type 'IteratorResult<[string, number] | [string, boolean], any>' is not assignable to type 'IteratorResult<readonly [string, number], any>'.
+          Type 'IteratorYieldResult<[string, number] | [string, boolean]>' is not assignable to type 'IteratorResult<readonly [string, number], any>'.
+            Type 'IteratorYieldResult<[string, number] | [string, boolean]>' is not assignable to type 'IteratorYieldResult<readonly [string, number]>'.
+              Type '[string, number] | [string, boolean]' is not assignable to type 'readonly [string, number]'.
+                Type '[string, boolean]' is not assignable to type 'readonly [string, number]'.
+                  Types of property '1' are incompatible.
+                    Type 'boolean' is not assignable to type 'number'.
   Overload 2 of 3, '(entries?: readonly (readonly [string, number])[]): Map<string, number>', gave the following error.
     Type 'true' is not assignable to type 'number'.
 
@@ -24,17 +20,13 @@ tests/cases/conformance/es6/destructuring/iterableArrayPattern28.ts(2,24): error
 !!! error TS2769: No overload matches this call.
 !!! error TS2769:   Overload 1 of 3, '(iterable: Iterable<readonly [string, number]>): Map<string, number>', gave the following error.
 !!! error TS2769:     Argument of type '([string, number] | [string, boolean])[]' is not assignable to parameter of type 'Iterable<readonly [string, number]>'.
-!!! error TS2769:       Types of property '[Symbol.iterator]' are incompatible.
-!!! error TS2769:         Type '() => IterableIterator<[string, number] | [string, boolean]>' is not assignable to type '() => Iterator<readonly [string, number], any, undefined>'.
-!!! error TS2769:           Type 'IterableIterator<[string, number] | [string, boolean]>' is not assignable to type 'Iterator<readonly [string, number], any, undefined>'.
-!!! error TS2769:             Types of property 'next' are incompatible.
-!!! error TS2769:               Type '(...args: [] | [undefined]) => IteratorResult<[string, number] | [string, boolean], any>' is not assignable to type '(...args: [] | [undefined]) => IteratorResult<readonly [string, number], any>'.
-!!! error TS2769:                 Type 'IteratorResult<[string, number] | [string, boolean], any>' is not assignable to type 'IteratorResult<readonly [string, number], any>'.
-!!! error TS2769:                   Type 'IteratorYieldResult<[string, number] | [string, boolean]>' is not assignable to type 'IteratorResult<readonly [string, number], any>'.
-!!! error TS2769:                     Type 'IteratorYieldResult<[string, number] | [string, boolean]>' is not assignable to type 'IteratorYieldResult<readonly [string, number]>'.
-!!! error TS2769:                       Type '[string, number] | [string, boolean]' is not assignable to type 'readonly [string, number]'.
-!!! error TS2769:                         Type '[string, boolean]' is not assignable to type 'readonly [string, number]'.
-!!! error TS2769:                           Types of property '1' are incompatible.
-!!! error TS2769:                             Type 'boolean' is not assignable to type 'number'.
+!!! error TS2769:       The types returned by '[Symbol.iterator]().next(...)' are incompatible between these types.
+!!! error TS2769:         Type 'IteratorResult<[string, number] | [string, boolean], any>' is not assignable to type 'IteratorResult<readonly [string, number], any>'.
+!!! error TS2769:           Type 'IteratorYieldResult<[string, number] | [string, boolean]>' is not assignable to type 'IteratorResult<readonly [string, number], any>'.
+!!! error TS2769:             Type 'IteratorYieldResult<[string, number] | [string, boolean]>' is not assignable to type 'IteratorYieldResult<readonly [string, number]>'.
+!!! error TS2769:               Type '[string, number] | [string, boolean]' is not assignable to type 'readonly [string, number]'.
+!!! error TS2769:                 Type '[string, boolean]' is not assignable to type 'readonly [string, number]'.
+!!! error TS2769:                   Types of property '1' are incompatible.
+!!! error TS2769:                     Type 'boolean' is not assignable to type 'number'.
 !!! error TS2769:   Overload 2 of 3, '(entries?: readonly (readonly [string, number])[]): Map<string, number>', gave the following error.
 !!! error TS2769:     Type 'true' is not assignable to type 'number'.
\ No newline at end of file
diff --git a/tests/baselines/reference/iteratorSpreadInArray6.errors.txt b/tests/baselines/reference/iteratorSpreadInArray6.errors.txt
index 0b114bc6477..202c0ab3bf2 100644
--- a/tests/baselines/reference/iteratorSpreadInArray6.errors.txt
+++ b/tests/baselines/reference/iteratorSpreadInArray6.errors.txt
@@ -1,10 +1,9 @@
 tests/cases/conformance/es6/spread/iteratorSpreadInArray6.ts(15,14): error TS2769: No overload matches this call.
   Overload 1 of 2, '(...items: ConcatArray<number>[]): number[]', gave the following error.
     Argument of type 'symbol[]' is not assignable to parameter of type 'ConcatArray<number>'.
-      Types of property 'slice' are incompatible.
-        Type '(start?: number, end?: number) => symbol[]' is not assignable to type '(start?: number, end?: number) => number[]'.
-          Type 'symbol[]' is not assignable to type 'number[]'.
-            Type 'symbol' is not assignable to type 'number'.
+      The types returned by 'slice(...)' are incompatible between these types.
+        Type 'symbol[]' is not assignable to type 'number[]'.
+          Type 'symbol' is not assignable to type 'number'.
   Overload 2 of 2, '(...items: (number | ConcatArray<number>)[]): number[]', gave the following error.
     Argument of type 'symbol[]' is not assignable to parameter of type 'number | ConcatArray<number>'.
       Type 'symbol[]' is not assignable to type 'ConcatArray<number>'.
@@ -30,10 +29,9 @@ tests/cases/conformance/es6/spread/iteratorSpreadInArray6.ts(15,14): error TS276
 !!! error TS2769: No overload matches this call.
 !!! error TS2769:   Overload 1 of 2, '(...items: ConcatArray<number>[]): number[]', gave the following error.
 !!! error TS2769:     Argument of type 'symbol[]' is not assignable to parameter of type 'ConcatArray<number>'.
-!!! error TS2769:       Types of property 'slice' are incompatible.
-!!! error TS2769:         Type '(start?: number, end?: number) => symbol[]' is not assignable to type '(start?: number, end?: number) => number[]'.
-!!! error TS2769:           Type 'symbol[]' is not assignable to type 'number[]'.
-!!! error TS2769:             Type 'symbol' is not assignable to type 'number'.
+!!! error TS2769:       The types returned by 'slice(...)' are incompatible between these types.
+!!! error TS2769:         Type 'symbol[]' is not assignable to type 'number[]'.
+!!! error TS2769:           Type 'symbol' is not assignable to type 'number'.
 !!! error TS2769:   Overload 2 of 2, '(...items: (number | ConcatArray<number>)[]): number[]', gave the following error.
 !!! error TS2769:     Argument of type 'symbol[]' is not assignable to parameter of type 'number | ConcatArray<number>'.
 !!! error TS2769:       Type 'symbol[]' is not assignable to type 'ConcatArray<number>'.
\ No newline at end of file
diff --git a/tests/baselines/reference/mergedDeclarations7.errors.txt b/tests/baselines/reference/mergedDeclarations7.errors.txt
index cd9b3a5e939..bc09ea081a3 100644
--- a/tests/baselines/reference/mergedDeclarations7.errors.txt
+++ b/tests/baselines/reference/mergedDeclarations7.errors.txt
@@ -1,7 +1,6 @@
 tests/cases/compiler/test.ts(4,5): error TS2322: Type 'PassportStatic' is not assignable to type 'Passport'.
-  Types of property 'use' are incompatible.
-    Type '() => PassportStatic' is not assignable to type '() => this'.
-      Type 'PassportStatic' is not assignable to type 'this'.
+  The types returned by 'use()' are incompatible between these types.
+    Type 'PassportStatic' is not assignable to type 'this'.
 
 
 ==== tests/cases/compiler/passport.d.ts (0 errors) ====
@@ -27,6 +26,5 @@ tests/cases/compiler/test.ts(4,5): error TS2322: Type 'PassportStatic' is not as
     let p: Passport = passport.use();
         ~
 !!! error TS2322: Type 'PassportStatic' is not assignable to type 'Passport'.
-!!! error TS2322:   Types of property 'use' are incompatible.
-!!! error TS2322:     Type '() => PassportStatic' is not assignable to type '() => this'.
-!!! error TS2322:       Type 'PassportStatic' is not assignable to type 'this'.
\ No newline at end of file
+!!! error TS2322:   The types returned by 'use()' are incompatible between these types.
+!!! error TS2322:     Type 'PassportStatic' is not assignable to type 'this'.
\ No newline at end of file
diff --git a/tests/baselines/reference/multiLineErrors.errors.txt b/tests/baselines/reference/multiLineErrors.errors.txt
index 70366aeabed..851425baef4 100644
--- a/tests/baselines/reference/multiLineErrors.errors.txt
+++ b/tests/baselines/reference/multiLineErrors.errors.txt
@@ -1,9 +1,7 @@
 tests/cases/compiler/multiLineErrors.ts(3,22): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
 tests/cases/compiler/multiLineErrors.ts(21,1): error TS2322: Type 'A2' is not assignable to type 'A1'.
-  Types of property 'x' are incompatible.
-    Type '{ y: string; }' is not assignable to type '{ y: number; }'.
-      Types of property 'y' are incompatible.
-        Type 'string' is not assignable to type 'number'.
+  The types of 'x.y' are incompatible between these types.
+    Type 'string' is not assignable to type 'number'.
 
 
 ==== tests/cases/compiler/multiLineErrors.ts (2 errors) ====
@@ -35,8 +33,6 @@ tests/cases/compiler/multiLineErrors.ts(21,1): error TS2322: Type 'A2' is not as
     t1 = t2;
     ~~
 !!! error TS2322: Type 'A2' is not assignable to type 'A1'.
-!!! error TS2322:   Types of property 'x' are incompatible.
-!!! error TS2322:     Type '{ y: string; }' is not assignable to type '{ y: number; }'.
-!!! error TS2322:       Types of property 'y' are incompatible.
-!!! error TS2322:         Type 'string' is not assignable to type 'number'.
+!!! error TS2322:   The types of 'x.y' are incompatible between these types.
+!!! error TS2322:     Type 'string' is not assignable to type 'number'.
     
\ No newline at end of file
diff --git a/tests/baselines/reference/mutuallyRecursiveCallbacks.errors.txt b/tests/baselines/reference/mutuallyRecursiveCallbacks.errors.txt
index bb90bcee999..63a568bf10a 100644
--- a/tests/baselines/reference/mutuallyRecursiveCallbacks.errors.txt
+++ b/tests/baselines/reference/mutuallyRecursiveCallbacks.errors.txt
@@ -1,9 +1,8 @@
 tests/cases/compiler/mutuallyRecursiveCallbacks.ts(7,1): error TS2322: Type '<T>(bar: Bar<T>) => void' is not assignable to type 'Bar<{}>'.
   Types of parameters 'bar' and 'foo' are incompatible.
     Types of parameters 'bar' and 'foo' are incompatible.
-      Type 'Foo<unknown>' is not assignable to type 'Bar<{}>'.
-        Types of parameters 'bar' and 'foo' are incompatible.
-          Type 'void' is not assignable to type 'Foo<unknown>'.
+      Types of parameters 'bar' and 'foo' are incompatible.
+        Type 'void' is not assignable to type 'Foo<unknown>'.
 
 
 ==== tests/cases/compiler/mutuallyRecursiveCallbacks.ts (1 errors) ====
@@ -18,7 +17,6 @@ tests/cases/compiler/mutuallyRecursiveCallbacks.ts(7,1): error TS2322: Type '<T>
 !!! error TS2322: Type '<T>(bar: Bar<T>) => void' is not assignable to type 'Bar<{}>'.
 !!! error TS2322:   Types of parameters 'bar' and 'foo' are incompatible.
 !!! error TS2322:     Types of parameters 'bar' and 'foo' are incompatible.
-!!! error TS2322:       Type 'Foo<unknown>' is not assignable to type 'Bar<{}>'.
-!!! error TS2322:         Types of parameters 'bar' and 'foo' are incompatible.
-!!! error TS2322:           Type 'void' is not assignable to type 'Foo<unknown>'.
+!!! error TS2322:       Types of parameters 'bar' and 'foo' are incompatible.
+!!! error TS2322:         Type 'void' is not assignable to type 'Foo<unknown>'.
     
\ No newline at end of file
diff --git a/tests/baselines/reference/nestedCallbackErrorNotFlattened.errors.txt b/tests/baselines/reference/nestedCallbackErrorNotFlattened.errors.txt
new file mode 100644
index 00000000000..3749d3765b0
--- /dev/null
+++ b/tests/baselines/reference/nestedCallbackErrorNotFlattened.errors.txt
@@ -0,0 +1,20 @@
+tests/cases/compiler/nestedCallbackErrorNotFlattened.ts(6,1): error TS2322: Type '() => () => () => () => number' is not assignable to type '() => () => () => () => string'.
+  Call signature return types '() => () => () => number' and '() => () => () => string' are incompatible.
+    Call signature return types '() => () => number' and '() => () => string' are incompatible.
+      Call signature return types '() => number' and '() => string' are incompatible.
+        Type 'number' is not assignable to type 'string'.
+
+
+==== tests/cases/compiler/nestedCallbackErrorNotFlattened.ts (1 errors) ====
+    type Cb<T> = {noAlias: () => T}["noAlias"]; // `"noAlias"` here prevents an alias symbol from being made
+    // which means the comparison will definitely be structural, rather than by variance
+    
+    declare const x: Cb<Cb<Cb<Cb<number>>>>; // one more layer of `Cb` adn we'd get a `true` from the deeply-nested symbol check
+    declare let y: Cb<Cb<Cb<Cb<string>>>>;
+    y = x;
+    ~
+!!! error TS2322: Type '() => () => () => () => number' is not assignable to type '() => () => () => () => string'.
+!!! error TS2322:   Call signature return types '() => () => () => number' and '() => () => () => string' are incompatible.
+!!! error TS2322:     Call signature return types '() => () => number' and '() => () => string' are incompatible.
+!!! error TS2322:       Call signature return types '() => number' and '() => string' are incompatible.
+!!! error TS2322:         Type 'number' is not assignable to type 'string'.
\ No newline at end of file
diff --git a/tests/baselines/reference/nestedCallbackErrorNotFlattened.js b/tests/baselines/reference/nestedCallbackErrorNotFlattened.js
new file mode 100644
index 00000000000..0c5edf9760b
--- /dev/null
+++ b/tests/baselines/reference/nestedCallbackErrorNotFlattened.js
@@ -0,0 +1,11 @@
+//// [nestedCallbackErrorNotFlattened.ts]
+type Cb<T> = {noAlias: () => T}["noAlias"]; // `"noAlias"` here prevents an alias symbol from being made
+// which means the comparison will definitely be structural, rather than by variance
+
+declare const x: Cb<Cb<Cb<Cb<number>>>>; // one more layer of `Cb` adn we'd get a `true` from the deeply-nested symbol check
+declare let y: Cb<Cb<Cb<Cb<string>>>>;
+y = x;
+
+//// [nestedCallbackErrorNotFlattened.js]
+"use strict";
+y = x;
diff --git a/tests/baselines/reference/nestedCallbackErrorNotFlattened.symbols b/tests/baselines/reference/nestedCallbackErrorNotFlattened.symbols
new file mode 100644
index 00000000000..2019b787822
--- /dev/null
+++ b/tests/baselines/reference/nestedCallbackErrorNotFlattened.symbols
@@ -0,0 +1,27 @@
+=== tests/cases/compiler/nestedCallbackErrorNotFlattened.ts ===
+type Cb<T> = {noAlias: () => T}["noAlias"]; // `"noAlias"` here prevents an alias symbol from being made
+>Cb : Symbol(Cb, Decl(nestedCallbackErrorNotFlattened.ts, 0, 0))
+>T : Symbol(T, Decl(nestedCallbackErrorNotFlattened.ts, 0, 8))
+>noAlias : Symbol(noAlias, Decl(nestedCallbackErrorNotFlattened.ts, 0, 14))
+>T : Symbol(T, Decl(nestedCallbackErrorNotFlattened.ts, 0, 8))
+
+// which means the comparison will definitely be structural, rather than by variance
+
+declare const x: Cb<Cb<Cb<Cb<number>>>>; // one more layer of `Cb` adn we'd get a `true` from the deeply-nested symbol check
+>x : Symbol(x, Decl(nestedCallbackErrorNotFlattened.ts, 3, 13))
+>Cb : Symbol(Cb, Decl(nestedCallbackErrorNotFlattened.ts, 0, 0))
+>Cb : Symbol(Cb, Decl(nestedCallbackErrorNotFlattened.ts, 0, 0))
+>Cb : Symbol(Cb, Decl(nestedCallbackErrorNotFlattened.ts, 0, 0))
+>Cb : Symbol(Cb, Decl(nestedCallbackErrorNotFlattened.ts, 0, 0))
+
+declare let y: Cb<Cb<Cb<Cb<string>>>>;
+>y : Symbol(y, Decl(nestedCallbackErrorNotFlattened.ts, 4, 11))
+>Cb : Symbol(Cb, Decl(nestedCallbackErrorNotFlattened.ts, 0, 0))
+>Cb : Symbol(Cb, Decl(nestedCallbackErrorNotFlattened.ts, 0, 0))
+>Cb : Symbol(Cb, Decl(nestedCallbackErrorNotFlattened.ts, 0, 0))
+>Cb : Symbol(Cb, Decl(nestedCallbackErrorNotFlattened.ts, 0, 0))
+
+y = x;
+>y : Symbol(y, Decl(nestedCallbackErrorNotFlattened.ts, 4, 11))
+>x : Symbol(x, Decl(nestedCallbackErrorNotFlattened.ts, 3, 13))
+
diff --git a/tests/baselines/reference/nestedCallbackErrorNotFlattened.types b/tests/baselines/reference/nestedCallbackErrorNotFlattened.types
new file mode 100644
index 00000000000..5e753714b34
--- /dev/null
+++ b/tests/baselines/reference/nestedCallbackErrorNotFlattened.types
@@ -0,0 +1,18 @@
+=== tests/cases/compiler/nestedCallbackErrorNotFlattened.ts ===
+type Cb<T> = {noAlias: () => T}["noAlias"]; // `"noAlias"` here prevents an alias symbol from being made
+>Cb : () => T
+>noAlias : () => T
+
+// which means the comparison will definitely be structural, rather than by variance
+
+declare const x: Cb<Cb<Cb<Cb<number>>>>; // one more layer of `Cb` adn we'd get a `true` from the deeply-nested symbol check
+>x : () => () => () => () => number
+
+declare let y: Cb<Cb<Cb<Cb<string>>>>;
+>y : () => () => () => () => string
+
+y = x;
+>y = x : () => () => () => () => number
+>y : () => () => () => () => string
+>x : () => () => () => () => number
+
diff --git a/tests/baselines/reference/nestedRecursiveArraysOrObjectsError01.errors.txt b/tests/baselines/reference/nestedRecursiveArraysOrObjectsError01.errors.txt
index 138a4a84158..650a808e598 100644
--- a/tests/baselines/reference/nestedRecursiveArraysOrObjectsError01.errors.txt
+++ b/tests/baselines/reference/nestedRecursiveArraysOrObjectsError01.errors.txt
@@ -1,17 +1,14 @@
 tests/cases/compiler/nestedRecursiveArraysOrObjectsError01.ts(10,9): error TS2322: Type '{ foo: string; jj: number; }[][][]' is not assignable to type 'Style'.
   Type '{ foo: string; jj: number; }[][][]' is not assignable to type 'StyleArray'.
-    Types of property 'pop' are incompatible.
-      Type '() => { foo: string; jj: number; }[][]' is not assignable to type '() => Style'.
-        Type '{ foo: string; jj: number; }[][]' is not assignable to type 'Style'.
-          Type '{ foo: string; jj: number; }[][]' is not assignable to type 'StyleArray'.
-            Types of property 'pop' are incompatible.
-              Type '() => { foo: string; jj: number; }[]' is not assignable to type '() => Style'.
-                Type '{ foo: string; jj: number; }[]' is not assignable to type 'Style'.
-                  Type '{ foo: string; jj: number; }[]' is not assignable to type 'StyleArray'.
-                    Types of property 'pop' are incompatible.
-                      Type '() => { foo: string; jj: number; }' is not assignable to type '() => Style'.
-                        Type '{ foo: string; jj: number; }' is not assignable to type 'Style'.
-                          Object literal may only specify known properties, and 'jj' does not exist in type 'Style'.
+    The types returned by 'pop()' are incompatible between these types.
+      Type '{ foo: string; jj: number; }[][]' is not assignable to type 'Style'.
+        Type '{ foo: string; jj: number; }[][]' is not assignable to type 'StyleArray'.
+          The types returned by 'pop()' are incompatible between these types.
+            Type '{ foo: string; jj: number; }[]' is not assignable to type 'Style'.
+              Type '{ foo: string; jj: number; }[]' is not assignable to type 'StyleArray'.
+                The types returned by 'pop()' are incompatible between these types.
+                  Type '{ foo: string; jj: number; }' is not assignable to type 'Style'.
+                    Object literal may only specify known properties, and 'jj' does not exist in type 'Style'.
 
 
 ==== tests/cases/compiler/nestedRecursiveArraysOrObjectsError01.ts (1 errors) ====
@@ -28,18 +25,15 @@ tests/cases/compiler/nestedRecursiveArraysOrObjectsError01.ts(10,9): error TS232
             ~~~~~
 !!! error TS2322: Type '{ foo: string; jj: number; }[][][]' is not assignable to type 'Style'.
 !!! error TS2322:   Type '{ foo: string; jj: number; }[][][]' is not assignable to type 'StyleArray'.
-!!! error TS2322:     Types of property 'pop' are incompatible.
-!!! error TS2322:       Type '() => { foo: string; jj: number; }[][]' is not assignable to type '() => Style'.
-!!! error TS2322:         Type '{ foo: string; jj: number; }[][]' is not assignable to type 'Style'.
-!!! error TS2322:           Type '{ foo: string; jj: number; }[][]' is not assignable to type 'StyleArray'.
-!!! error TS2322:             Types of property 'pop' are incompatible.
-!!! error TS2322:               Type '() => { foo: string; jj: number; }[]' is not assignable to type '() => Style'.
-!!! error TS2322:                 Type '{ foo: string; jj: number; }[]' is not assignable to type 'Style'.
-!!! error TS2322:                   Type '{ foo: string; jj: number; }[]' is not assignable to type 'StyleArray'.
-!!! error TS2322:                     Types of property 'pop' are incompatible.
-!!! error TS2322:                       Type '() => { foo: string; jj: number; }' is not assignable to type '() => Style'.
-!!! error TS2322:                         Type '{ foo: string; jj: number; }' is not assignable to type 'Style'.
-!!! error TS2322:                           Object literal may only specify known properties, and 'jj' does not exist in type 'Style'.
+!!! error TS2322:     The types returned by 'pop()' are incompatible between these types.
+!!! error TS2322:       Type '{ foo: string; jj: number; }[][]' is not assignable to type 'Style'.
+!!! error TS2322:         Type '{ foo: string; jj: number; }[][]' is not assignable to type 'StyleArray'.
+!!! error TS2322:           The types returned by 'pop()' are incompatible between these types.
+!!! error TS2322:             Type '{ foo: string; jj: number; }[]' is not assignable to type 'Style'.
+!!! error TS2322:               Type '{ foo: string; jj: number; }[]' is not assignable to type 'StyleArray'.
+!!! error TS2322:                 The types returned by 'pop()' are incompatible between these types.
+!!! error TS2322:                   Type '{ foo: string; jj: number; }' is not assignable to type 'Style'.
+!!! error TS2322:                     Object literal may only specify known properties, and 'jj' does not exist in type 'Style'.
         }]]
     ];
     
diff --git a/tests/baselines/reference/objectTypeHidingMembersOfObjectAssignmentCompat.errors.txt b/tests/baselines/reference/objectTypeHidingMembersOfObjectAssignmentCompat.errors.txt
index c4ee3ea17b2..d4afd97723e 100644
--- a/tests/baselines/reference/objectTypeHidingMembersOfObjectAssignmentCompat.errors.txt
+++ b/tests/baselines/reference/objectTypeHidingMembersOfObjectAssignmentCompat.errors.txt
@@ -1,15 +1,12 @@
 tests/cases/conformance/types/members/objectTypeHidingMembersOfObjectAssignmentCompat.ts(7,1): error TS2322: Type 'I' is not assignable to type 'Object'.
-  Types of property 'toString' are incompatible.
-    Type '() => void' is not assignable to type '() => string'.
-      Type 'void' is not assignable to type 'string'.
+  The types returned by 'toString()' are incompatible between these types.
+    Type 'void' is not assignable to type 'string'.
 tests/cases/conformance/types/members/objectTypeHidingMembersOfObjectAssignmentCompat.ts(14,1): error TS2322: Type 'C' is not assignable to type 'Object'.
-  Types of property 'toString' are incompatible.
-    Type '() => void' is not assignable to type '() => string'.
-      Type 'void' is not assignable to type 'string'.
+  The types returned by 'toString()' are incompatible between these types.
+    Type 'void' is not assignable to type 'string'.
 tests/cases/conformance/types/members/objectTypeHidingMembersOfObjectAssignmentCompat.ts(20,1): error TS2322: Type '{ toString: () => void; }' is not assignable to type 'Object'.
-  Types of property 'toString' are incompatible.
-    Type '() => void' is not assignable to type '() => string'.
-      Type 'void' is not assignable to type 'string'.
+  The types returned by 'toString()' are incompatible between these types.
+    Type 'void' is not assignable to type 'string'.
 
 
 ==== tests/cases/conformance/types/members/objectTypeHidingMembersOfObjectAssignmentCompat.ts (3 errors) ====
@@ -22,9 +19,8 @@ tests/cases/conformance/types/members/objectTypeHidingMembersOfObjectAssignmentC
     o = i; // error
     ~
 !!! error TS2322: Type 'I' is not assignable to type 'Object'.
-!!! error TS2322:   Types of property 'toString' are incompatible.
-!!! error TS2322:     Type '() => void' is not assignable to type '() => string'.
-!!! error TS2322:       Type 'void' is not assignable to type 'string'.
+!!! error TS2322:   The types returned by 'toString()' are incompatible between these types.
+!!! error TS2322:     Type 'void' is not assignable to type 'string'.
     i = o; // ok
     
     class C {
@@ -34,9 +30,8 @@ tests/cases/conformance/types/members/objectTypeHidingMembersOfObjectAssignmentC
     o = c; // error
     ~
 !!! error TS2322: Type 'C' is not assignable to type 'Object'.
-!!! error TS2322:   Types of property 'toString' are incompatible.
-!!! error TS2322:     Type '() => void' is not assignable to type '() => string'.
-!!! error TS2322:       Type 'void' is not assignable to type 'string'.
+!!! error TS2322:   The types returned by 'toString()' are incompatible between these types.
+!!! error TS2322:     Type 'void' is not assignable to type 'string'.
     c = o; // ok
     
     var a = {
@@ -45,7 +40,6 @@ tests/cases/conformance/types/members/objectTypeHidingMembersOfObjectAssignmentC
     o = a; // error
     ~
 !!! error TS2322: Type '{ toString: () => void; }' is not assignable to type 'Object'.
-!!! error TS2322:   Types of property 'toString' are incompatible.
-!!! error TS2322:     Type '() => void' is not assignable to type '() => string'.
-!!! error TS2322:       Type 'void' is not assignable to type 'string'.
+!!! error TS2322:   The types returned by 'toString()' are incompatible between these types.
+!!! error TS2322:     Type 'void' is not assignable to type 'string'.
     a = o; // ok
\ No newline at end of file
diff --git a/tests/baselines/reference/objectTypeHidingMembersOfObjectAssignmentCompat2.errors.txt b/tests/baselines/reference/objectTypeHidingMembersOfObjectAssignmentCompat2.errors.txt
index 3e27b22240e..28d466457d7 100644
--- a/tests/baselines/reference/objectTypeHidingMembersOfObjectAssignmentCompat2.errors.txt
+++ b/tests/baselines/reference/objectTypeHidingMembersOfObjectAssignmentCompat2.errors.txt
@@ -1,25 +1,18 @@
 tests/cases/conformance/types/members/objectTypeHidingMembersOfObjectAssignmentCompat2.ts(7,1): error TS2322: Type 'I' is not assignable to type 'Object'.
-  Types of property 'toString' are incompatible.
-    Type '() => number' is not assignable to type '() => string'.
-      Type 'number' is not assignable to type 'string'.
-tests/cases/conformance/types/members/objectTypeHidingMembersOfObjectAssignmentCompat2.ts(8,1): error TS2322: Type 'Object' is not assignable to type 'I'.
-  The 'Object' type is assignable to very few other types. Did you mean to use the 'any' type instead?
-    Types of property 'toString' are incompatible.
-      Type '() => string' is not assignable to type '() => number'.
-        Type 'string' is not assignable to type 'number'.
+  The types returned by 'toString()' are incompatible between these types.
+    Type 'number' is not assignable to type 'string'.
+tests/cases/conformance/types/members/objectTypeHidingMembersOfObjectAssignmentCompat2.ts(8,1): error TS2696: The 'Object' type is assignable to very few other types. Did you mean to use the 'any' type instead?
+  The types returned by 'toString()' are incompatible between these types.
+    Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/types/members/objectTypeHidingMembersOfObjectAssignmentCompat2.ts(14,1): error TS2322: Type 'C' is not assignable to type 'Object'.
-  Types of property 'toString' are incompatible.
-    Type '() => number' is not assignable to type '() => string'.
-      Type 'number' is not assignable to type 'string'.
-tests/cases/conformance/types/members/objectTypeHidingMembersOfObjectAssignmentCompat2.ts(15,1): error TS2322: Type 'Object' is not assignable to type 'C'.
-  The 'Object' type is assignable to very few other types. Did you mean to use the 'any' type instead?
-    Types of property 'toString' are incompatible.
-      Type '() => string' is not assignable to type '() => number'.
-        Type 'string' is not assignable to type 'number'.
+  The types returned by 'toString()' are incompatible between these types.
+    Type 'number' is not assignable to type 'string'.
+tests/cases/conformance/types/members/objectTypeHidingMembersOfObjectAssignmentCompat2.ts(15,1): error TS2696: The 'Object' type is assignable to very few other types. Did you mean to use the 'any' type instead?
+  The types returned by 'toString()' are incompatible between these types.
+    Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/types/members/objectTypeHidingMembersOfObjectAssignmentCompat2.ts(20,1): error TS2322: Type '{ toString: () => void; }' is not assignable to type 'Object'.
-  Types of property 'toString' are incompatible.
-    Type '() => void' is not assignable to type '() => string'.
-      Type 'void' is not assignable to type 'string'.
+  The types returned by 'toString()' are incompatible between these types.
+    Type 'void' is not assignable to type 'string'.
 
 
 ==== tests/cases/conformance/types/members/objectTypeHidingMembersOfObjectAssignmentCompat2.ts (5 errors) ====
@@ -32,16 +25,13 @@ tests/cases/conformance/types/members/objectTypeHidingMembersOfObjectAssignmentC
     o = i; // error
     ~
 !!! error TS2322: Type 'I' is not assignable to type 'Object'.
-!!! error TS2322:   Types of property 'toString' are incompatible.
-!!! error TS2322:     Type '() => number' is not assignable to type '() => string'.
-!!! error TS2322:       Type 'number' is not assignable to type 'string'.
+!!! error TS2322:   The types returned by 'toString()' are incompatible between these types.
+!!! error TS2322:     Type 'number' is not assignable to type 'string'.
     i = o; // error
     ~
-!!! error TS2322: Type 'Object' is not assignable to type 'I'.
-!!! error TS2322:   The 'Object' type is assignable to very few other types. Did you mean to use the 'any' type instead?
-!!! error TS2322:     Types of property 'toString' are incompatible.
-!!! error TS2322:       Type '() => string' is not assignable to type '() => number'.
-!!! error TS2322:         Type 'string' is not assignable to type 'number'.
+!!! error TS2696: The 'Object' type is assignable to very few other types. Did you mean to use the 'any' type instead?
+!!! error TS2696:   The types returned by 'toString()' are incompatible between these types.
+!!! error TS2696:     Type 'string' is not assignable to type 'number'.
     
     class C {
         toString(): number { return 1; }
@@ -50,16 +40,13 @@ tests/cases/conformance/types/members/objectTypeHidingMembersOfObjectAssignmentC
     o = c; // error
     ~
 !!! error TS2322: Type 'C' is not assignable to type 'Object'.
-!!! error TS2322:   Types of property 'toString' are incompatible.
-!!! error TS2322:     Type '() => number' is not assignable to type '() => string'.
-!!! error TS2322:       Type 'number' is not assignable to type 'string'.
+!!! error TS2322:   The types returned by 'toString()' are incompatible between these types.
+!!! error TS2322:     Type 'number' is not assignable to type 'string'.
     c = o; // error
     ~
-!!! error TS2322: Type 'Object' is not assignable to type 'C'.
-!!! error TS2322:   The 'Object' type is assignable to very few other types. Did you mean to use the 'any' type instead?
-!!! error TS2322:     Types of property 'toString' are incompatible.
-!!! error TS2322:       Type '() => string' is not assignable to type '() => number'.
-!!! error TS2322:         Type 'string' is not assignable to type 'number'.
+!!! error TS2696: The 'Object' type is assignable to very few other types. Did you mean to use the 'any' type instead?
+!!! error TS2696:   The types returned by 'toString()' are incompatible between these types.
+!!! error TS2696:     Type 'string' is not assignable to type 'number'.
     
     var a = {
         toString: () => { }
@@ -67,7 +54,6 @@ tests/cases/conformance/types/members/objectTypeHidingMembersOfObjectAssignmentC
     o = a; // error
     ~
 !!! error TS2322: Type '{ toString: () => void; }' is not assignable to type 'Object'.
-!!! error TS2322:   Types of property 'toString' are incompatible.
-!!! error TS2322:     Type '() => void' is not assignable to type '() => string'.
-!!! error TS2322:       Type 'void' is not assignable to type 'string'.
+!!! error TS2322:   The types returned by 'toString()' are incompatible between these types.
+!!! error TS2322:     Type 'void' is not assignable to type 'string'.
     a = o; // ok
\ No newline at end of file
diff --git a/tests/baselines/reference/promisePermutations.errors.txt b/tests/baselines/reference/promisePermutations.errors.txt
index 1cb61562fe3..87743ab77a3 100644
--- a/tests/baselines/reference/promisePermutations.errors.txt
+++ b/tests/baselines/reference/promisePermutations.errors.txt
@@ -122,8 +122,8 @@ tests/cases/compiler/promisePermutations.ts(159,21): error TS2769: No overload m
 tests/cases/compiler/promisePermutations.ts(160,21): error TS2769: No overload matches this call.
   The last overload gave the following error.
     Argument of type '{ (x: number): Promise<number>; (x: string): Promise<string>; }' is not assignable to parameter of type '(value: number) => IPromise<string>'.
-      Type 'Promise<number>' is not assignable to type 'IPromise<string>'.
-        Types of property 'then' are incompatible.
+      Call signature return types 'Promise<number>' and 'IPromise<string>' are incompatible.
+        The types of 'then' are incompatible between these types.
           Type '{ <TResult1 = number, TResult2 = never>(onfulfilled?: (value: number) => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>): Promise<TResult1 | TResult2>; <U>(success?: (value: number) => Promise<U>, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => Promise<U>, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => U, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => U, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; }' is not assignable to type '{ <U>(success?: (value: string) => IPromise<U>, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => IPromise<U>, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => U, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => U, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>; }'.
             Types of parameters 'onfulfilled' and 'success' are incompatible.
               Types of parameters 'value' and 'value' are incompatible.
@@ -481,8 +481,8 @@ tests/cases/compiler/promisePermutations.ts(160,21): error TS2769: No overload m
 !!! error TS2769: No overload matches this call.
 !!! error TS2769:   The last overload gave the following error.
 !!! error TS2769:     Argument of type '{ (x: number): Promise<number>; (x: string): Promise<string>; }' is not assignable to parameter of type '(value: number) => IPromise<string>'.
-!!! error TS2769:       Type 'Promise<number>' is not assignable to type 'IPromise<string>'.
-!!! error TS2769:         Types of property 'then' are incompatible.
+!!! error TS2769:       Call signature return types 'Promise<number>' and 'IPromise<string>' are incompatible.
+!!! error TS2769:         The types of 'then' are incompatible between these types.
 !!! error TS2769:           Type '{ <TResult1 = number, TResult2 = never>(onfulfilled?: (value: number) => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>): Promise<TResult1 | TResult2>; <U>(success?: (value: number) => Promise<U>, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => Promise<U>, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => U, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => U, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; }' is not assignable to type '{ <U>(success?: (value: string) => IPromise<U>, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => IPromise<U>, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => U, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => U, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>; }'.
 !!! error TS2769:             Types of parameters 'onfulfilled' and 'success' are incompatible.
 !!! error TS2769:               Types of parameters 'value' and 'value' are incompatible.
diff --git a/tests/baselines/reference/promisePermutations2.errors.txt b/tests/baselines/reference/promisePermutations2.errors.txt
index d601a5049bf..b69eaab3157 100644
--- a/tests/baselines/reference/promisePermutations2.errors.txt
+++ b/tests/baselines/reference/promisePermutations2.errors.txt
@@ -80,8 +80,8 @@ tests/cases/compiler/promisePermutations2.ts(158,21): error TS2345: Argument of
   Type 'Promise<number>' is not assignable to type 'Promise<string>'.
     Type 'number' is not assignable to type 'string'.
 tests/cases/compiler/promisePermutations2.ts(159,21): error TS2345: Argument of type '{ (x: number): Promise<number>; (x: string): Promise<string>; }' is not assignable to parameter of type '(value: number) => IPromise<string>'.
-  Type 'Promise<number>' is not assignable to type 'IPromise<string>'.
-    Types of property 'then' are incompatible.
+  Call signature return types 'Promise<number>' and 'IPromise<string>' are incompatible.
+    The types of 'then' are incompatible between these types.
       Type '{ <TResult1 = number, TResult2 = never>(onfulfilled?: (value: number) => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>): Promise<TResult1 | TResult2>; <U>(success?: (value: number) => U, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; }' is not assignable to type '{ <U>(success?: (value: string) => IPromise<U>, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => IPromise<U>, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => U, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => U, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>; }'.
         Types of parameters 'onfulfilled' and 'success' are incompatible.
           Types of parameters 'value' and 'value' are incompatible.
@@ -376,8 +376,8 @@ tests/cases/compiler/promisePermutations2.ts(159,21): error TS2345: Argument of
     var s11c = s11.then(testFunction11P, testFunction11, testFunction11); // ok
                         ~~~~~~~~~~~~~~~
 !!! error TS2345: Argument of type '{ (x: number): Promise<number>; (x: string): Promise<string>; }' is not assignable to parameter of type '(value: number) => IPromise<string>'.
-!!! error TS2345:   Type 'Promise<number>' is not assignable to type 'IPromise<string>'.
-!!! error TS2345:     Types of property 'then' are incompatible.
+!!! error TS2345:   Call signature return types 'Promise<number>' and 'IPromise<string>' are incompatible.
+!!! error TS2345:     The types of 'then' are incompatible between these types.
 !!! error TS2345:       Type '{ <TResult1 = number, TResult2 = never>(onfulfilled?: (value: number) => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>): Promise<TResult1 | TResult2>; <U>(success?: (value: number) => U, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; }' is not assignable to type '{ <U>(success?: (value: string) => IPromise<U>, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => IPromise<U>, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => U, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>; <U>(success?: (value: string) => U, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>; }'.
 !!! error TS2345:         Types of parameters 'onfulfilled' and 'success' are incompatible.
 !!! error TS2345:           Types of parameters 'value' and 'value' are incompatible.
diff --git a/tests/baselines/reference/promisePermutations3.errors.txt b/tests/baselines/reference/promisePermutations3.errors.txt
index d3574d2a4c3..929b0d5459c 100644
--- a/tests/baselines/reference/promisePermutations3.errors.txt
+++ b/tests/baselines/reference/promisePermutations3.errors.txt
@@ -101,8 +101,8 @@ tests/cases/compiler/promisePermutations3.ts(158,21): error TS2769: No overload
 tests/cases/compiler/promisePermutations3.ts(159,21): error TS2769: No overload matches this call.
   The last overload gave the following error.
     Argument of type '{ (x: number): Promise<number>; (x: string): Promise<string>; }' is not assignable to parameter of type '(value: number) => IPromise<string>'.
-      Type 'Promise<number>' is not assignable to type 'IPromise<string>'.
-        Types of property 'then' are incompatible.
+      Call signature return types 'Promise<number>' and 'IPromise<string>' are incompatible.
+        The types of 'then' are incompatible between these types.
           Type '{ <TResult1 = number, TResult2 = never>(onfulfilled?: (value: number) => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>): Promise<TResult1 | TResult2>; <U>(success?: (value: number) => Promise<U>, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => Promise<U>, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => U, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => U, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; }' is not assignable to type '<U>(success?: (value: string) => U, error?: (error: any) => U, progress?: (progress: any) => void) => IPromise<U>'.
             Types of parameters 'onfulfilled' and 'success' are incompatible.
               Types of parameters 'value' and 'value' are incompatible.
@@ -429,8 +429,8 @@ tests/cases/compiler/promisePermutations3.ts(165,21): error TS2345: Argument of
 !!! error TS2769: No overload matches this call.
 !!! error TS2769:   The last overload gave the following error.
 !!! error TS2769:     Argument of type '{ (x: number): Promise<number>; (x: string): Promise<string>; }' is not assignable to parameter of type '(value: number) => IPromise<string>'.
-!!! error TS2769:       Type 'Promise<number>' is not assignable to type 'IPromise<string>'.
-!!! error TS2769:         Types of property 'then' are incompatible.
+!!! error TS2769:       Call signature return types 'Promise<number>' and 'IPromise<string>' are incompatible.
+!!! error TS2769:         The types of 'then' are incompatible between these types.
 !!! error TS2769:           Type '{ <TResult1 = number, TResult2 = never>(onfulfilled?: (value: number) => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>): Promise<TResult1 | TResult2>; <U>(success?: (value: number) => Promise<U>, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => Promise<U>, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => U, error?: (error: any) => Promise<U>, progress?: (progress: any) => void): Promise<U>; <U>(success?: (value: number) => U, error?: (error: any) => U, progress?: (progress: any) => void): Promise<U>; }' is not assignable to type '<U>(success?: (value: string) => U, error?: (error: any) => U, progress?: (progress: any) => void) => IPromise<U>'.
 !!! error TS2769:             Types of parameters 'onfulfilled' and 'success' are incompatible.
 !!! error TS2769:               Types of parameters 'value' and 'value' are incompatible.
diff --git a/tests/baselines/reference/promiseTypeInference.errors.txt b/tests/baselines/reference/promiseTypeInference.errors.txt
index 04ba3a0d878..7056e35432f 100644
--- a/tests/baselines/reference/promiseTypeInference.errors.txt
+++ b/tests/baselines/reference/promiseTypeInference.errors.txt
@@ -5,10 +5,9 @@ tests/cases/compiler/promiseTypeInference.ts(10,39): error TS2769: No overload m
     Type 'IPromise<number>' is not assignable to type 'number | PromiseLike<number>'.
       Type 'IPromise<number>' is not assignable to type 'PromiseLike<number>'.
         Types of property 'then' are incompatible.
-          Type '<U>(success?: (value: number) => IPromise<U>) => IPromise<U>' is not assignable to type '<TResult1 = number, TResult2 = never>(onfulfilled?: (value: number) => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => PromiseLike<TResult1 | TResult2>'.
-            Types of parameters 'success' and 'onfulfilled' are incompatible.
-              Type 'TResult1 | PromiseLike<TResult1>' is not assignable to type 'IPromise<TResult1 | TResult2>'.
-                Type 'TResult1' is not assignable to type 'IPromise<TResult1 | TResult2>'.
+          Types of parameters 'success' and 'onfulfilled' are incompatible.
+            Type 'TResult1 | PromiseLike<TResult1>' is not assignable to type 'IPromise<TResult1 | TResult2>'.
+              Type 'TResult1' is not assignable to type 'IPromise<TResult1 | TResult2>'.
 
 
 ==== tests/cases/compiler/promiseTypeInference.ts (1 errors) ====
@@ -30,10 +29,9 @@ tests/cases/compiler/promiseTypeInference.ts(10,39): error TS2769: No overload m
 !!! error TS2769:     Type 'IPromise<number>' is not assignable to type 'number | PromiseLike<number>'.
 !!! error TS2769:       Type 'IPromise<number>' is not assignable to type 'PromiseLike<number>'.
 !!! error TS2769:         Types of property 'then' are incompatible.
-!!! error TS2769:           Type '<U>(success?: (value: number) => IPromise<U>) => IPromise<U>' is not assignable to type '<TResult1 = number, TResult2 = never>(onfulfilled?: (value: number) => TResult1 | PromiseLike<TResult1>, onrejected?: (reason: any) => TResult2 | PromiseLike<TResult2>) => PromiseLike<TResult1 | TResult2>'.
-!!! error TS2769:             Types of parameters 'success' and 'onfulfilled' are incompatible.
-!!! error TS2769:               Type 'TResult1 | PromiseLike<TResult1>' is not assignable to type 'IPromise<TResult1 | TResult2>'.
-!!! error TS2769:                 Type 'TResult1' is not assignable to type 'IPromise<TResult1 | TResult2>'.
+!!! error TS2769:           Types of parameters 'success' and 'onfulfilled' are incompatible.
+!!! error TS2769:             Type 'TResult1 | PromiseLike<TResult1>' is not assignable to type 'IPromise<TResult1 | TResult2>'.
+!!! error TS2769:               Type 'TResult1' is not assignable to type 'IPromise<TResult1 | TResult2>'.
 !!! related TS2728 /.ts/lib.es5.d.ts:1413:5: 'catch' is declared here.
 !!! related TS6502 tests/cases/compiler/promiseTypeInference.ts:2:23: The expected type comes from the return type of this signature.
 !!! related TS6502 /.ts/lib.es5.d.ts:1406:57: The expected type comes from the return type of this signature.
diff --git a/tests/baselines/reference/strictFunctionTypesErrors.errors.txt b/tests/baselines/reference/strictFunctionTypesErrors.errors.txt
index 3ff04c44fb7..6f474663dcb 100644
--- a/tests/baselines/reference/strictFunctionTypesErrors.errors.txt
+++ b/tests/baselines/reference/strictFunctionTypesErrors.errors.txt
@@ -69,9 +69,8 @@ tests/cases/compiler/strictFunctionTypesErrors.ts(126,1): error TS2322: Type 'Cr
 tests/cases/compiler/strictFunctionTypesErrors.ts(127,1): error TS2322: Type 'Crate<Animal>' is not assignable to type 'Crate<Dog>'.
   Types of property 'item' are incompatible.
     Type 'Animal' is not assignable to type 'Dog'.
-tests/cases/compiler/strictFunctionTypesErrors.ts(133,1): error TS2322: Type '(f: (x: Dog) => Dog) => void' is not assignable to type '(f: (x: Animal) => Animal) => void'.
-  Types of parameters 'f' and 'f' are incompatible.
-    Type 'Animal' is not assignable to type 'Dog'.
+tests/cases/compiler/strictFunctionTypesErrors.ts(133,1): error TS2328: Types of parameters 'f' and 'f' are incompatible.
+  Type 'Animal' is not assignable to type 'Dog'.
 tests/cases/compiler/strictFunctionTypesErrors.ts(134,1): error TS2322: Type '(f: (x: Animal) => Animal) => void' is not assignable to type '(f: (x: Dog) => Dog) => void'.
   Types of parameters 'f' and 'f' are incompatible.
     Types of parameters 'x' and 'x' are incompatible.
@@ -324,9 +323,8 @@ tests/cases/compiler/strictFunctionTypesErrors.ts(155,5): error TS2322: Type '(c
     declare let fc2: (f: (x: Dog) => Dog) => void;
     fc1 = fc2;  // Error
     ~~~
-!!! error TS2322: Type '(f: (x: Dog) => Dog) => void' is not assignable to type '(f: (x: Animal) => Animal) => void'.
-!!! error TS2322:   Types of parameters 'f' and 'f' are incompatible.
-!!! error TS2322:     Type 'Animal' is not assignable to type 'Dog'.
+!!! error TS2328: Types of parameters 'f' and 'f' are incompatible.
+!!! error TS2328:   Type 'Animal' is not assignable to type 'Dog'.
     fc2 = fc1;  // Error
     ~~~
 !!! error TS2322: Type '(f: (x: Animal) => Animal) => void' is not assignable to type '(f: (x: Dog) => Dog) => void'.
diff --git a/tests/baselines/reference/subtypingWithCallSignaturesWithSpecializedSignatures.errors.txt b/tests/baselines/reference/subtypingWithCallSignaturesWithSpecializedSignatures.errors.txt
index 7dfb078170a..b8bc5100402 100644
--- a/tests/baselines/reference/subtypingWithCallSignaturesWithSpecializedSignatures.errors.txt
+++ b/tests/baselines/reference/subtypingWithCallSignaturesWithSpecializedSignatures.errors.txt
@@ -1,12 +1,10 @@
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithCallSignaturesWithSpecializedSignatures.ts(70,15): error TS2430: Interface 'I2' incorrectly extends interface 'Base2'.
-  Types of property 'a' are incompatible.
-    Type '(x: string) => string' is not assignable to type '{ (x: "a"): number; (x: string): number; }'.
-      Type 'string' is not assignable to type 'number'.
+  The types returned by 'a(...)' are incompatible between these types.
+    Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithCallSignaturesWithSpecializedSignatures.ts(76,15): error TS2430: Interface 'I3' incorrectly extends interface 'Base2'.
-  Types of property 'a2' are incompatible.
-    Type '<T>(x: T) => string' is not assignable to type '<T>(x: T) => T'.
-      Type 'string' is not assignable to type 'T'.
-        'string' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+  The types returned by 'a2(...)' are incompatible between these types.
+    Type 'string' is not assignable to type 'T'.
+      'string' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
 
 
 ==== tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithCallSignaturesWithSpecializedSignatures.ts (2 errors) ====
@@ -82,9 +80,8 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
         interface I2 extends Base2 {
                   ~~
 !!! error TS2430: Interface 'I2' incorrectly extends interface 'Base2'.
-!!! error TS2430:   Types of property 'a' are incompatible.
-!!! error TS2430:     Type '(x: string) => string' is not assignable to type '{ (x: "a"): number; (x: string): number; }'.
-!!! error TS2430:       Type 'string' is not assignable to type 'number'.
+!!! error TS2430:   The types returned by 'a(...)' are incompatible between these types.
+!!! error TS2430:     Type 'string' is not assignable to type 'number'.
             // N's
             a: (x: string) => string; // error because base returns non-void;
         }
@@ -93,10 +90,9 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
         interface I3 extends Base2 {
                   ~~
 !!! error TS2430: Interface 'I3' incorrectly extends interface 'Base2'.
-!!! error TS2430:   Types of property 'a2' are incompatible.
-!!! error TS2430:     Type '<T>(x: T) => string' is not assignable to type '<T>(x: T) => T'.
-!!! error TS2430:       Type 'string' is not assignable to type 'T'.
-!!! error TS2430:         'string' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+!!! error TS2430:   The types returned by 'a2(...)' are incompatible between these types.
+!!! error TS2430:     Type 'string' is not assignable to type 'T'.
+!!! error TS2430:       'string' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
             // N's
             a2: <T>(x: T) => string; // error because base returns non-void;
         }
diff --git a/tests/baselines/reference/subtypingWithConstructSignaturesWithSpecializedSignatures.errors.txt b/tests/baselines/reference/subtypingWithConstructSignaturesWithSpecializedSignatures.errors.txt
index 8f4a219407a..db493045f09 100644
--- a/tests/baselines/reference/subtypingWithConstructSignaturesWithSpecializedSignatures.errors.txt
+++ b/tests/baselines/reference/subtypingWithConstructSignaturesWithSpecializedSignatures.errors.txt
@@ -1,12 +1,10 @@
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithConstructSignaturesWithSpecializedSignatures.ts(70,15): error TS2430: Interface 'I2' incorrectly extends interface 'Base2'.
-  Types of property 'a' are incompatible.
-    Type 'new (x: string) => string' is not assignable to type '{ new (x: "a"): number; new (x: string): number; }'.
-      Type 'string' is not assignable to type 'number'.
+  The types returned by 'new a(...)' are incompatible between these types.
+    Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithConstructSignaturesWithSpecializedSignatures.ts(76,15): error TS2430: Interface 'I3' incorrectly extends interface 'Base2'.
-  Types of property 'a2' are incompatible.
-    Type 'new <T>(x: T) => string' is not assignable to type 'new <T>(x: T) => T'.
-      Type 'string' is not assignable to type 'T'.
-        'string' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+  The types returned by 'new a2(...)' are incompatible between these types.
+    Type 'string' is not assignable to type 'T'.
+      'string' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
 
 
 ==== tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithConstructSignaturesWithSpecializedSignatures.ts (2 errors) ====
@@ -82,9 +80,8 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
         interface I2 extends Base2 {
                   ~~
 !!! error TS2430: Interface 'I2' incorrectly extends interface 'Base2'.
-!!! error TS2430:   Types of property 'a' are incompatible.
-!!! error TS2430:     Type 'new (x: string) => string' is not assignable to type '{ new (x: "a"): number; new (x: string): number; }'.
-!!! error TS2430:       Type 'string' is not assignable to type 'number'.
+!!! error TS2430:   The types returned by 'new a(...)' are incompatible between these types.
+!!! error TS2430:     Type 'string' is not assignable to type 'number'.
             // N's
             a: new (x: string) => string; // error because base returns non-void;
         }
@@ -93,10 +90,9 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
         interface I3 extends Base2 {
                   ~~
 !!! error TS2430: Interface 'I3' incorrectly extends interface 'Base2'.
-!!! error TS2430:   Types of property 'a2' are incompatible.
-!!! error TS2430:     Type 'new <T>(x: T) => string' is not assignable to type 'new <T>(x: T) => T'.
-!!! error TS2430:       Type 'string' is not assignable to type 'T'.
-!!! error TS2430:         'string' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+!!! error TS2430:   The types returned by 'new a2(...)' are incompatible between these types.
+!!! error TS2430:     Type 'string' is not assignable to type 'T'.
+!!! error TS2430:       'string' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
             // N's
             a2: new <T>(x: T) => string; // error because base returns non-void;
         }
diff --git a/tests/baselines/reference/subtypingWithGenericCallSignaturesWithOptionalParameters.errors.txt b/tests/baselines/reference/subtypingWithGenericCallSignaturesWithOptionalParameters.errors.txt
index 36380fc97f4..4e0ef2113ec 100644
--- a/tests/baselines/reference/subtypingWithGenericCallSignaturesWithOptionalParameters.errors.txt
+++ b/tests/baselines/reference/subtypingWithGenericCallSignaturesWithOptionalParameters.errors.txt
@@ -5,23 +5,20 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
   Types of property 'a3' are incompatible.
     Type '(x: T, y: T) => T' is not assignable to type '(x: T) => T'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithGenericCallSignaturesWithOptionalParameters.ts(100,15): error TS2430: Interface 'I1<T>' incorrectly extends interface 'Base2'.
-  Types of property 'a' are incompatible.
-    Type '() => T' is not assignable to type '<T>() => T'.
-      Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
-        'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+  The types returned by 'a()' are incompatible between these types.
+    Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
+      'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithGenericCallSignaturesWithOptionalParameters.ts(104,15): error TS2430: Interface 'I2<T>' incorrectly extends interface 'Base2'.
-  Types of property 'a' are incompatible.
-    Type '(x?: T) => T' is not assignable to type '<T>() => T'.
-      Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
-        'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+  The types returned by 'a(...)' are incompatible between these types.
+    Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
+      'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithGenericCallSignaturesWithOptionalParameters.ts(108,15): error TS2430: Interface 'I3<T>' incorrectly extends interface 'Base2'.
   Types of property 'a' are incompatible.
     Type '(x: T) => T' is not assignable to type '<T>() => T'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithGenericCallSignaturesWithOptionalParameters.ts(113,15): error TS2430: Interface 'I4<T>' incorrectly extends interface 'Base2'.
-  Types of property 'a2' are incompatible.
-    Type '() => T' is not assignable to type '<T>(x?: T) => T'.
-      Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
-        'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+  The types returned by 'a2(...)' are incompatible between these types.
+    Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
+      'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithGenericCallSignaturesWithOptionalParameters.ts(117,15): error TS2430: Interface 'I5<T>' incorrectly extends interface 'Base2'.
   Types of property 'a2' are incompatible.
     Type '(x?: T) => T' is not assignable to type '<T>(x?: T) => T'.
@@ -35,10 +32,9 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
         Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
           'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithGenericCallSignaturesWithOptionalParameters.ts(126,15): error TS2430: Interface 'I7<T>' incorrectly extends interface 'Base2'.
-  Types of property 'a3' are incompatible.
-    Type '() => T' is not assignable to type '<T>(x: T) => T'.
-      Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
-        'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+  The types returned by 'a3(...)' are incompatible between these types.
+    Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
+      'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithGenericCallSignaturesWithOptionalParameters.ts(130,15): error TS2430: Interface 'I8<T>' incorrectly extends interface 'Base2'.
   Types of property 'a3' are incompatible.
     Type '(x?: T) => T' is not assignable to type '<T>(x: T) => T'.
@@ -55,10 +51,9 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
   Types of property 'a3' are incompatible.
     Type '(x: T, y: T) => T' is not assignable to type '<T>(x: T) => T'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithGenericCallSignaturesWithOptionalParameters.ts(143,15): error TS2430: Interface 'I11<T>' incorrectly extends interface 'Base2'.
-  Types of property 'a4' are incompatible.
-    Type '() => T' is not assignable to type '<T>(x: T, y?: T) => T'.
-      Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
-        'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+  The types returned by 'a4(...)' are incompatible between these types.
+    Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
+      'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithGenericCallSignaturesWithOptionalParameters.ts(147,15): error TS2430: Interface 'I12<T>' incorrectly extends interface 'Base2'.
   Types of property 'a4' are incompatible.
     Type '(x?: T, y?: T) => T' is not assignable to type '<T>(x: T, y?: T) => T'.
@@ -78,10 +73,9 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
         Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
           'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithGenericCallSignaturesWithOptionalParameters.ts(160,15): error TS2430: Interface 'I15<T>' incorrectly extends interface 'Base2'.
-  Types of property 'a5' are incompatible.
-    Type '() => T' is not assignable to type '<T>(x?: T, y?: T) => T'.
-      Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
-        'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+  The types returned by 'a5(...)' are incompatible between these types.
+    Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
+      'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithGenericCallSignaturesWithOptionalParameters.ts(164,15): error TS2430: Interface 'I16<T>' incorrectly extends interface 'Base2'.
   Types of property 'a5' are incompatible.
     Type '(x?: T, y?: T) => T' is not assignable to type '<T>(x?: T, y?: T) => T'.
@@ -219,20 +213,18 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
         interface I1<T> extends Base2 {
                   ~~
 !!! error TS2430: Interface 'I1<T>' incorrectly extends interface 'Base2'.
-!!! error TS2430:   Types of property 'a' are incompatible.
-!!! error TS2430:     Type '() => T' is not assignable to type '<T>() => T'.
-!!! error TS2430:       Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
-!!! error TS2430:         'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+!!! error TS2430:   The types returned by 'a()' are incompatible between these types.
+!!! error TS2430:     Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
+!!! error TS2430:       'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
             a: () => T; 
         }
     
         interface I2<T> extends Base2 {
                   ~~
 !!! error TS2430: Interface 'I2<T>' incorrectly extends interface 'Base2'.
-!!! error TS2430:   Types of property 'a' are incompatible.
-!!! error TS2430:     Type '(x?: T) => T' is not assignable to type '<T>() => T'.
-!!! error TS2430:       Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
-!!! error TS2430:         'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+!!! error TS2430:   The types returned by 'a(...)' are incompatible between these types.
+!!! error TS2430:     Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
+!!! error TS2430:       'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
             a: (x?: T) => T;
         }
     
@@ -248,10 +240,9 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
         interface I4<T> extends Base2 {
                   ~~
 !!! error TS2430: Interface 'I4<T>' incorrectly extends interface 'Base2'.
-!!! error TS2430:   Types of property 'a2' are incompatible.
-!!! error TS2430:     Type '() => T' is not assignable to type '<T>(x?: T) => T'.
-!!! error TS2430:       Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
-!!! error TS2430:         'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+!!! error TS2430:   The types returned by 'a2(...)' are incompatible between these types.
+!!! error TS2430:     Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
+!!! error TS2430:       'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
             a2: () => T; 
         }
     
@@ -281,10 +272,9 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
         interface I7<T> extends Base2 {
                   ~~
 !!! error TS2430: Interface 'I7<T>' incorrectly extends interface 'Base2'.
-!!! error TS2430:   Types of property 'a3' are incompatible.
-!!! error TS2430:     Type '() => T' is not assignable to type '<T>(x: T) => T'.
-!!! error TS2430:       Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
-!!! error TS2430:         'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+!!! error TS2430:   The types returned by 'a3(...)' are incompatible between these types.
+!!! error TS2430:     Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
+!!! error TS2430:       'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
             a3: () => T;
         }
     
@@ -322,10 +312,9 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
         interface I11<T> extends Base2 {
                   ~~~
 !!! error TS2430: Interface 'I11<T>' incorrectly extends interface 'Base2'.
-!!! error TS2430:   Types of property 'a4' are incompatible.
-!!! error TS2430:     Type '() => T' is not assignable to type '<T>(x: T, y?: T) => T'.
-!!! error TS2430:       Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
-!!! error TS2430:         'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+!!! error TS2430:   The types returned by 'a4(...)' are incompatible between these types.
+!!! error TS2430:     Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
+!!! error TS2430:       'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
             a4: () => T; 
         }
     
@@ -366,10 +355,9 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
         interface I15<T> extends Base2 {
                   ~~~
 !!! error TS2430: Interface 'I15<T>' incorrectly extends interface 'Base2'.
-!!! error TS2430:   Types of property 'a5' are incompatible.
-!!! error TS2430:     Type '() => T' is not assignable to type '<T>(x?: T, y?: T) => T'.
-!!! error TS2430:       Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
-!!! error TS2430:         'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+!!! error TS2430:   The types returned by 'a5(...)' are incompatible between these types.
+!!! error TS2430:     Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
+!!! error TS2430:       'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
             a5: () => T; 
         }
     
diff --git a/tests/baselines/reference/subtypingWithGenericConstructSignaturesWithOptionalParameters.errors.txt b/tests/baselines/reference/subtypingWithGenericConstructSignaturesWithOptionalParameters.errors.txt
index 427c7c1f19e..7481ba54f1e 100644
--- a/tests/baselines/reference/subtypingWithGenericConstructSignaturesWithOptionalParameters.errors.txt
+++ b/tests/baselines/reference/subtypingWithGenericConstructSignaturesWithOptionalParameters.errors.txt
@@ -5,23 +5,20 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
   Types of property 'a3' are incompatible.
     Type 'new (x: T, y: T) => T' is not assignable to type 'new (x: T) => T'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithGenericConstructSignaturesWithOptionalParameters.ts(100,15): error TS2430: Interface 'I1<T>' incorrectly extends interface 'Base2'.
-  Types of property 'a' are incompatible.
-    Type 'new () => T' is not assignable to type 'new <T>() => T'.
-      Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
-        'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+  The types returned by 'new a()' are incompatible between these types.
+    Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
+      'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithGenericConstructSignaturesWithOptionalParameters.ts(104,15): error TS2430: Interface 'I2<T>' incorrectly extends interface 'Base2'.
-  Types of property 'a' are incompatible.
-    Type 'new (x?: T) => T' is not assignable to type 'new <T>() => T'.
-      Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
-        'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+  The types returned by 'new a(...)' are incompatible between these types.
+    Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
+      'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithGenericConstructSignaturesWithOptionalParameters.ts(108,15): error TS2430: Interface 'I3<T>' incorrectly extends interface 'Base2'.
   Types of property 'a' are incompatible.
     Type 'new (x: T) => T' is not assignable to type 'new <T>() => T'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithGenericConstructSignaturesWithOptionalParameters.ts(113,15): error TS2430: Interface 'I4<T>' incorrectly extends interface 'Base2'.
-  Types of property 'a2' are incompatible.
-    Type 'new () => T' is not assignable to type 'new <T>(x?: T) => T'.
-      Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
-        'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+  The types returned by 'new a2(...)' are incompatible between these types.
+    Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
+      'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithGenericConstructSignaturesWithOptionalParameters.ts(117,15): error TS2430: Interface 'I5<T>' incorrectly extends interface 'Base2'.
   Types of property 'a2' are incompatible.
     Type 'new (x?: T) => T' is not assignable to type 'new <T>(x?: T) => T'.
@@ -35,10 +32,9 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
         Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
           'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithGenericConstructSignaturesWithOptionalParameters.ts(126,15): error TS2430: Interface 'I7<T>' incorrectly extends interface 'Base2'.
-  Types of property 'a3' are incompatible.
-    Type 'new () => T' is not assignable to type 'new <T>(x: T) => T'.
-      Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
-        'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+  The types returned by 'new a3(...)' are incompatible between these types.
+    Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
+      'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithGenericConstructSignaturesWithOptionalParameters.ts(130,15): error TS2430: Interface 'I8<T>' incorrectly extends interface 'Base2'.
   Types of property 'a3' are incompatible.
     Type 'new (x?: T) => T' is not assignable to type 'new <T>(x: T) => T'.
@@ -55,10 +51,9 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
   Types of property 'a3' are incompatible.
     Type 'new (x: T, y: T) => T' is not assignable to type 'new <T>(x: T) => T'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithGenericConstructSignaturesWithOptionalParameters.ts(143,15): error TS2430: Interface 'I11<T>' incorrectly extends interface 'Base2'.
-  Types of property 'a4' are incompatible.
-    Type 'new () => T' is not assignable to type 'new <T>(x: T, y?: T) => T'.
-      Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
-        'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+  The types returned by 'new a4(...)' are incompatible between these types.
+    Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
+      'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithGenericConstructSignaturesWithOptionalParameters.ts(147,15): error TS2430: Interface 'I12<T>' incorrectly extends interface 'Base2'.
   Types of property 'a4' are incompatible.
     Type 'new (x?: T, y?: T) => T' is not assignable to type 'new <T>(x: T, y?: T) => T'.
@@ -78,10 +73,9 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
         Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
           'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithGenericConstructSignaturesWithOptionalParameters.ts(160,15): error TS2430: Interface 'I15<T>' incorrectly extends interface 'Base2'.
-  Types of property 'a5' are incompatible.
-    Type 'new () => T' is not assignable to type 'new <T>(x?: T, y?: T) => T'.
-      Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
-        'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+  The types returned by 'new a5(...)' are incompatible between these types.
+    Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
+      'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithGenericConstructSignaturesWithOptionalParameters.ts(164,15): error TS2430: Interface 'I16<T>' incorrectly extends interface 'Base2'.
   Types of property 'a5' are incompatible.
     Type 'new (x?: T, y?: T) => T' is not assignable to type 'new <T>(x?: T, y?: T) => T'.
@@ -219,20 +213,18 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
         interface I1<T> extends Base2 {
                   ~~
 !!! error TS2430: Interface 'I1<T>' incorrectly extends interface 'Base2'.
-!!! error TS2430:   Types of property 'a' are incompatible.
-!!! error TS2430:     Type 'new () => T' is not assignable to type 'new <T>() => T'.
-!!! error TS2430:       Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
-!!! error TS2430:         'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+!!! error TS2430:   The types returned by 'new a()' are incompatible between these types.
+!!! error TS2430:     Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
+!!! error TS2430:       'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
             a: new () => T; 
         }
     
         interface I2<T> extends Base2 {
                   ~~
 !!! error TS2430: Interface 'I2<T>' incorrectly extends interface 'Base2'.
-!!! error TS2430:   Types of property 'a' are incompatible.
-!!! error TS2430:     Type 'new (x?: T) => T' is not assignable to type 'new <T>() => T'.
-!!! error TS2430:       Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
-!!! error TS2430:         'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+!!! error TS2430:   The types returned by 'new a(...)' are incompatible between these types.
+!!! error TS2430:     Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
+!!! error TS2430:       'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
             a: new (x?: T) => T;
         }
     
@@ -248,10 +240,9 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
         interface I4<T> extends Base2 {
                   ~~
 !!! error TS2430: Interface 'I4<T>' incorrectly extends interface 'Base2'.
-!!! error TS2430:   Types of property 'a2' are incompatible.
-!!! error TS2430:     Type 'new () => T' is not assignable to type 'new <T>(x?: T) => T'.
-!!! error TS2430:       Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
-!!! error TS2430:         'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+!!! error TS2430:   The types returned by 'new a2(...)' are incompatible between these types.
+!!! error TS2430:     Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
+!!! error TS2430:       'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
             a2: new () => T; 
         }
     
@@ -281,10 +272,9 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
         interface I7<T> extends Base2 {
                   ~~
 !!! error TS2430: Interface 'I7<T>' incorrectly extends interface 'Base2'.
-!!! error TS2430:   Types of property 'a3' are incompatible.
-!!! error TS2430:     Type 'new () => T' is not assignable to type 'new <T>(x: T) => T'.
-!!! error TS2430:       Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
-!!! error TS2430:         'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+!!! error TS2430:   The types returned by 'new a3(...)' are incompatible between these types.
+!!! error TS2430:     Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
+!!! error TS2430:       'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
             a3: new () => T;
         }
     
@@ -322,10 +312,9 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
         interface I11<T> extends Base2 {
                   ~~~
 !!! error TS2430: Interface 'I11<T>' incorrectly extends interface 'Base2'.
-!!! error TS2430:   Types of property 'a4' are incompatible.
-!!! error TS2430:     Type 'new () => T' is not assignable to type 'new <T>(x: T, y?: T) => T'.
-!!! error TS2430:       Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
-!!! error TS2430:         'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+!!! error TS2430:   The types returned by 'new a4(...)' are incompatible between these types.
+!!! error TS2430:     Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
+!!! error TS2430:       'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
             a4: new () => T; 
         }
     
@@ -366,10 +355,9 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
         interface I15<T> extends Base2 {
                   ~~~
 !!! error TS2430: Interface 'I15<T>' incorrectly extends interface 'Base2'.
-!!! error TS2430:   Types of property 'a5' are incompatible.
-!!! error TS2430:     Type 'new () => T' is not assignable to type 'new <T>(x?: T, y?: T) => T'.
-!!! error TS2430:       Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
-!!! error TS2430:         'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
+!!! error TS2430:   The types returned by 'new a5(...)' are incompatible between these types.
+!!! error TS2430:     Type 'T' is not assignable to type 'T'. Two different types with this name exist, but they are unrelated.
+!!! error TS2430:       'T' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
             a5: new () => T; 
         }
     
diff --git a/tests/baselines/reference/typeParameterArgumentEquivalence5.errors.txt b/tests/baselines/reference/typeParameterArgumentEquivalence5.errors.txt
index e5196d3d4a5..b832ce6cb7c 100644
--- a/tests/baselines/reference/typeParameterArgumentEquivalence5.errors.txt
+++ b/tests/baselines/reference/typeParameterArgumentEquivalence5.errors.txt
@@ -1,9 +1,9 @@
 tests/cases/compiler/typeParameterArgumentEquivalence5.ts(4,5): error TS2322: Type '() => (item: any) => T' is not assignable to type '() => (item: any) => U'.
-  Type '(item: any) => T' is not assignable to type '(item: any) => U'.
+  Call signature return types '(item: any) => T' and '(item: any) => U' are incompatible.
     Type 'T' is not assignable to type 'U'.
       'T' is assignable to the constraint of type 'U', but 'U' could be instantiated with a different subtype of constraint '{}'.
 tests/cases/compiler/typeParameterArgumentEquivalence5.ts(5,5): error TS2322: Type '() => (item: any) => U' is not assignable to type '() => (item: any) => T'.
-  Type '(item: any) => U' is not assignable to type '(item: any) => T'.
+  Call signature return types '(item: any) => U' and '(item: any) => T' are incompatible.
     Type 'U' is not assignable to type 'T'.
       'U' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
 
@@ -15,13 +15,13 @@ tests/cases/compiler/typeParameterArgumentEquivalence5.ts(5,5): error TS2322: Ty
         x = y;  // Should be an error
         ~
 !!! error TS2322: Type '() => (item: any) => T' is not assignable to type '() => (item: any) => U'.
-!!! error TS2322:   Type '(item: any) => T' is not assignable to type '(item: any) => U'.
+!!! error TS2322:   Call signature return types '(item: any) => T' and '(item: any) => U' are incompatible.
 !!! error TS2322:     Type 'T' is not assignable to type 'U'.
 !!! error TS2322:       'T' is assignable to the constraint of type 'U', but 'U' could be instantiated with a different subtype of constraint '{}'.
         y = x;  // Shound be an error
         ~
 !!! error TS2322: Type '() => (item: any) => U' is not assignable to type '() => (item: any) => T'.
-!!! error TS2322:   Type '(item: any) => U' is not assignable to type '(item: any) => T'.
+!!! error TS2322:   Call signature return types '(item: any) => U' and '(item: any) => T' are incompatible.
 !!! error TS2322:     Type 'U' is not assignable to type 'T'.
 !!! error TS2322:       'U' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '{}'.
     }
diff --git a/tests/baselines/reference/types.asyncGenerators.es2018.2.errors.txt b/tests/baselines/reference/types.asyncGenerators.es2018.2.errors.txt
index 9f22060b9e9..3d588abf1ee 100644
--- a/tests/baselines/reference/types.asyncGenerators.es2018.2.errors.txt
+++ b/tests/baselines/reference/types.asyncGenerators.es2018.2.errors.txt
@@ -1,39 +1,29 @@
 tests/cases/conformance/types/asyncGenerators/types.asyncGenerators.es2018.2.ts(2,12): error TS2504: Type '{}' must have a '[Symbol.asyncIterator]()' method that returns an async iterator.
 tests/cases/conformance/types/asyncGenerators/types.asyncGenerators.es2018.2.ts(8,12): error TS2504: Type 'Promise<number[]>' must have a '[Symbol.asyncIterator]()' method that returns an async iterator.
 tests/cases/conformance/types/asyncGenerators/types.asyncGenerators.es2018.2.ts(10,7): error TS2322: Type '() => AsyncGenerator<string, void, undefined>' is not assignable to type '() => AsyncIterableIterator<number>'.
-  Type 'AsyncGenerator<string, void, undefined>' is not assignable to type 'AsyncIterableIterator<number>'.
-    Types of property 'next' are incompatible.
-      Type '(...args: [] | [undefined]) => Promise<IteratorResult<string, void>>' is not assignable to type '(...args: [] | [undefined]) => Promise<IteratorResult<number, any>>'.
-        Type 'Promise<IteratorResult<string, void>>' is not assignable to type 'Promise<IteratorResult<number, any>>'.
-          Type 'IteratorResult<string, void>' is not assignable to type 'IteratorResult<number, any>'.
-            Type 'IteratorYieldResult<string>' is not assignable to type 'IteratorResult<number, any>'.
-              Type 'IteratorYieldResult<string>' is not assignable to type 'IteratorYieldResult<number>'.
-                Type 'string' is not assignable to type 'number'.
+  Call signature return types 'AsyncGenerator<string, void, undefined>' and 'AsyncIterableIterator<number>' are incompatible.
+    The types returned by 'next(...)' are incompatible between these types.
+      Type 'Promise<IteratorResult<string, void>>' is not assignable to type 'Promise<IteratorResult<number, any>>'.
+        Type 'IteratorResult<string, void>' is not assignable to type 'IteratorResult<number, any>'.
+          Type 'IteratorYieldResult<string>' is not assignable to type 'IteratorResult<number, any>'.
+            Type 'IteratorYieldResult<string>' is not assignable to type 'IteratorYieldResult<number>'.
+              Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/types/asyncGenerators/types.asyncGenerators.es2018.2.ts(13,7): error TS2322: Type '() => AsyncGenerator<string, void, undefined>' is not assignable to type '() => AsyncIterableIterator<number>'.
   Type 'AsyncGenerator<string, void, undefined>' is not assignable to type 'AsyncIterableIterator<number>'.
 tests/cases/conformance/types/asyncGenerators/types.asyncGenerators.es2018.2.ts(16,7): error TS2322: Type '() => AsyncGenerator<string, void, unknown>' is not assignable to type '() => AsyncIterableIterator<number>'.
-  Type 'AsyncGenerator<string, void, unknown>' is not assignable to type 'AsyncIterableIterator<number>'.
-    Types of property 'next' are incompatible.
-      Type '(...args: [] | [unknown]) => Promise<IteratorResult<string, void>>' is not assignable to type '(...args: [] | [undefined]) => Promise<IteratorResult<number, any>>'.
-        Type 'Promise<IteratorResult<string, void>>' is not assignable to type 'Promise<IteratorResult<number, any>>'.
+  Call signature return types 'AsyncGenerator<string, void, unknown>' and 'AsyncIterableIterator<number>' are incompatible.
+    The types returned by 'next(...)' are incompatible between these types.
+      Type 'Promise<IteratorResult<string, void>>' is not assignable to type 'Promise<IteratorResult<number, any>>'.
 tests/cases/conformance/types/asyncGenerators/types.asyncGenerators.es2018.2.ts(19,7): error TS2322: Type '() => AsyncGenerator<string, void, undefined>' is not assignable to type '() => AsyncIterable<number>'.
-  Type 'AsyncGenerator<string, void, undefined>' is not assignable to type 'AsyncIterable<number>'.
-    Types of property '[Symbol.asyncIterator]' are incompatible.
-      Type '() => AsyncGenerator<string, void, undefined>' is not assignable to type '() => AsyncIterator<number, any, undefined>'.
-        Type 'AsyncGenerator<string, void, undefined>' is not assignable to type 'AsyncIterator<number, any, undefined>'.
-          Types of property 'next' are incompatible.
-            Type '(...args: [] | [undefined]) => Promise<IteratorResult<string, void>>' is not assignable to type '(...args: [] | [undefined]) => Promise<IteratorResult<number, any>>'.
-              Type 'Promise<IteratorResult<string, void>>' is not assignable to type 'Promise<IteratorResult<number, any>>'.
+  Call signature return types 'AsyncGenerator<string, void, undefined>' and 'AsyncIterable<number>' are incompatible.
+    The types returned by '[Symbol.asyncIterator]().next(...)' are incompatible between these types.
+      Type 'Promise<IteratorResult<string, void>>' is not assignable to type 'Promise<IteratorResult<number, any>>'.
 tests/cases/conformance/types/asyncGenerators/types.asyncGenerators.es2018.2.ts(22,7): error TS2322: Type '() => AsyncGenerator<string, void, undefined>' is not assignable to type '() => AsyncIterable<number>'.
   Type 'AsyncGenerator<string, void, undefined>' is not assignable to type 'AsyncIterable<number>'.
 tests/cases/conformance/types/asyncGenerators/types.asyncGenerators.es2018.2.ts(25,7): error TS2322: Type '() => AsyncGenerator<string, void, unknown>' is not assignable to type '() => AsyncIterable<number>'.
-  Type 'AsyncGenerator<string, void, unknown>' is not assignable to type 'AsyncIterable<number>'.
-    Types of property '[Symbol.asyncIterator]' are incompatible.
-      Type '() => AsyncGenerator<string, void, unknown>' is not assignable to type '() => AsyncIterator<number, any, undefined>'.
-        Type 'AsyncGenerator<string, void, unknown>' is not assignable to type 'AsyncIterator<number, any, undefined>'.
-          Types of property 'next' are incompatible.
-            Type '(...args: [] | [unknown]) => Promise<IteratorResult<string, void>>' is not assignable to type '(...args: [] | [undefined]) => Promise<IteratorResult<number, any>>'.
-              Type 'Promise<IteratorResult<string, void>>' is not assignable to type 'Promise<IteratorResult<number, any>>'.
+  Call signature return types 'AsyncGenerator<string, void, unknown>' and 'AsyncIterable<number>' are incompatible.
+    The types returned by '[Symbol.asyncIterator]().next(...)' are incompatible between these types.
+      Type 'Promise<IteratorResult<string, void>>' is not assignable to type 'Promise<IteratorResult<number, any>>'.
 tests/cases/conformance/types/asyncGenerators/types.asyncGenerators.es2018.2.ts(28,7): error TS2322: Type '() => AsyncGenerator<string, void, undefined>' is not assignable to type '() => AsyncIterator<number, any, undefined>'.
   Type 'AsyncGenerator<string, void, undefined>' is not assignable to type 'AsyncIterator<number, any, undefined>'.
 tests/cases/conformance/types/asyncGenerators/types.asyncGenerators.es2018.2.ts(31,7): error TS2322: Type '() => AsyncGenerator<string, void, undefined>' is not assignable to type '() => AsyncIterator<number, any, undefined>'.
@@ -52,10 +42,9 @@ tests/cases/conformance/types/asyncGenerators/types.asyncGenerators.es2018.2.ts(
 tests/cases/conformance/types/asyncGenerators/types.asyncGenerators.es2018.2.ts(64,42): error TS2741: Property '[Symbol.iterator]' is missing in type 'AsyncGenerator<number, any, undefined>' but required in type 'IterableIterator<number>'.
 tests/cases/conformance/types/asyncGenerators/types.asyncGenerators.es2018.2.ts(67,42): error TS2741: Property '[Symbol.iterator]' is missing in type 'AsyncGenerator<any, any, any>' but required in type 'Iterable<number>'.
 tests/cases/conformance/types/asyncGenerators/types.asyncGenerators.es2018.2.ts(70,42): error TS2322: Type 'AsyncGenerator<number, any, undefined>' is not assignable to type 'Iterator<number, any, undefined>'.
-  Types of property 'next' are incompatible.
-    Type '(...args: [] | [undefined]) => Promise<IteratorResult<number, any>>' is not assignable to type '(...args: [] | [undefined]) => IteratorResult<number, any>'.
-      Type 'Promise<IteratorResult<number, any>>' is not assignable to type 'IteratorResult<number, any>'.
-        Property 'value' is missing in type 'Promise<IteratorResult<number, any>>' but required in type 'IteratorYieldResult<number>'.
+  The types returned by 'next(...)' are incompatible between these types.
+    Type 'Promise<IteratorResult<number, any>>' is not assignable to type 'IteratorResult<number, any>'.
+      Property 'value' is missing in type 'Promise<IteratorResult<number, any>>' but required in type 'IteratorYieldResult<number>'.
 tests/cases/conformance/types/asyncGenerators/types.asyncGenerators.es2018.2.ts(74,12): error TS2504: Type '{}' must have a '[Symbol.asyncIterator]()' method that returns an async iterator.
 
 
@@ -77,14 +66,13 @@ tests/cases/conformance/types/asyncGenerators/types.asyncGenerators.es2018.2.ts(
     const assignability1: () => AsyncIterableIterator<number> = async function * () {
           ~~~~~~~~~~~~~~
 !!! error TS2322: Type '() => AsyncGenerator<string, void, undefined>' is not assignable to type '() => AsyncIterableIterator<number>'.
-!!! error TS2322:   Type 'AsyncGenerator<string, void, undefined>' is not assignable to type 'AsyncIterableIterator<number>'.
-!!! error TS2322:     Types of property 'next' are incompatible.
-!!! error TS2322:       Type '(...args: [] | [undefined]) => Promise<IteratorResult<string, void>>' is not assignable to type '(...args: [] | [undefined]) => Promise<IteratorResult<number, any>>'.
-!!! error TS2322:         Type 'Promise<IteratorResult<string, void>>' is not assignable to type 'Promise<IteratorResult<number, any>>'.
-!!! error TS2322:           Type 'IteratorResult<string, void>' is not assignable to type 'IteratorResult<number, any>'.
-!!! error TS2322:             Type 'IteratorYieldResult<string>' is not assignable to type 'IteratorResult<number, any>'.
-!!! error TS2322:               Type 'IteratorYieldResult<string>' is not assignable to type 'IteratorYieldResult<number>'.
-!!! error TS2322:                 Type 'string' is not assignable to type 'number'.
+!!! error TS2322:   Call signature return types 'AsyncGenerator<string, void, undefined>' and 'AsyncIterableIterator<number>' are incompatible.
+!!! error TS2322:     The types returned by 'next(...)' are incompatible between these types.
+!!! error TS2322:       Type 'Promise<IteratorResult<string, void>>' is not assignable to type 'Promise<IteratorResult<number, any>>'.
+!!! error TS2322:         Type 'IteratorResult<string, void>' is not assignable to type 'IteratorResult<number, any>'.
+!!! error TS2322:           Type 'IteratorYieldResult<string>' is not assignable to type 'IteratorResult<number, any>'.
+!!! error TS2322:             Type 'IteratorYieldResult<string>' is not assignable to type 'IteratorYieldResult<number>'.
+!!! error TS2322:               Type 'string' is not assignable to type 'number'.
         yield "a";
     };
     const assignability2: () => AsyncIterableIterator<number> = async function * () {
@@ -96,22 +84,17 @@ tests/cases/conformance/types/asyncGenerators/types.asyncGenerators.es2018.2.ts(
     const assignability3: () => AsyncIterableIterator<number> = async function * () {
           ~~~~~~~~~~~~~~
 !!! error TS2322: Type '() => AsyncGenerator<string, void, unknown>' is not assignable to type '() => AsyncIterableIterator<number>'.
-!!! error TS2322:   Type 'AsyncGenerator<string, void, unknown>' is not assignable to type 'AsyncIterableIterator<number>'.
-!!! error TS2322:     Types of property 'next' are incompatible.
-!!! error TS2322:       Type '(...args: [] | [unknown]) => Promise<IteratorResult<string, void>>' is not assignable to type '(...args: [] | [undefined]) => Promise<IteratorResult<number, any>>'.
-!!! error TS2322:         Type 'Promise<IteratorResult<string, void>>' is not assignable to type 'Promise<IteratorResult<number, any>>'.
+!!! error TS2322:   Call signature return types 'AsyncGenerator<string, void, unknown>' and 'AsyncIterableIterator<number>' are incompatible.
+!!! error TS2322:     The types returned by 'next(...)' are incompatible between these types.
+!!! error TS2322:       Type 'Promise<IteratorResult<string, void>>' is not assignable to type 'Promise<IteratorResult<number, any>>'.
         yield* (async function * () { yield "a"; })();
     };
     const assignability4: () => AsyncIterable<number> = async function * () {
           ~~~~~~~~~~~~~~
 !!! error TS2322: Type '() => AsyncGenerator<string, void, undefined>' is not assignable to type '() => AsyncIterable<number>'.
-!!! error TS2322:   Type 'AsyncGenerator<string, void, undefined>' is not assignable to type 'AsyncIterable<number>'.
-!!! error TS2322:     Types of property '[Symbol.asyncIterator]' are incompatible.
-!!! error TS2322:       Type '() => AsyncGenerator<string, void, undefined>' is not assignable to type '() => AsyncIterator<number, any, undefined>'.
-!!! error TS2322:         Type 'AsyncGenerator<string, void, undefined>' is not assignable to type 'AsyncIterator<number, any, undefined>'.
-!!! error TS2322:           Types of property 'next' are incompatible.
-!!! error TS2322:             Type '(...args: [] | [undefined]) => Promise<IteratorResult<string, void>>' is not assignable to type '(...args: [] | [undefined]) => Promise<IteratorResult<number, any>>'.
-!!! error TS2322:               Type 'Promise<IteratorResult<string, void>>' is not assignable to type 'Promise<IteratorResult<number, any>>'.
+!!! error TS2322:   Call signature return types 'AsyncGenerator<string, void, undefined>' and 'AsyncIterable<number>' are incompatible.
+!!! error TS2322:     The types returned by '[Symbol.asyncIterator]().next(...)' are incompatible between these types.
+!!! error TS2322:       Type 'Promise<IteratorResult<string, void>>' is not assignable to type 'Promise<IteratorResult<number, any>>'.
         yield "a";
     };
     const assignability5: () => AsyncIterable<number> = async function * () {
@@ -123,13 +106,9 @@ tests/cases/conformance/types/asyncGenerators/types.asyncGenerators.es2018.2.ts(
     const assignability6: () => AsyncIterable<number> = async function * () {
           ~~~~~~~~~~~~~~
 !!! error TS2322: Type '() => AsyncGenerator<string, void, unknown>' is not assignable to type '() => AsyncIterable<number>'.
-!!! error TS2322:   Type 'AsyncGenerator<string, void, unknown>' is not assignable to type 'AsyncIterable<number>'.
-!!! error TS2322:     Types of property '[Symbol.asyncIterator]' are incompatible.
-!!! error TS2322:       Type '() => AsyncGenerator<string, void, unknown>' is not assignable to type '() => AsyncIterator<number, any, undefined>'.
-!!! error TS2322:         Type 'AsyncGenerator<string, void, unknown>' is not assignable to type 'AsyncIterator<number, any, undefined>'.
-!!! error TS2322:           Types of property 'next' are incompatible.
-!!! error TS2322:             Type '(...args: [] | [unknown]) => Promise<IteratorResult<string, void>>' is not assignable to type '(...args: [] | [undefined]) => Promise<IteratorResult<number, any>>'.
-!!! error TS2322:               Type 'Promise<IteratorResult<string, void>>' is not assignable to type 'Promise<IteratorResult<number, any>>'.
+!!! error TS2322:   Call signature return types 'AsyncGenerator<string, void, unknown>' and 'AsyncIterable<number>' are incompatible.
+!!! error TS2322:     The types returned by '[Symbol.asyncIterator]().next(...)' are incompatible between these types.
+!!! error TS2322:       Type 'Promise<IteratorResult<string, void>>' is not assignable to type 'Promise<IteratorResult<number, any>>'.
         yield* (async function * () { yield "a"; })();
     };
     const assignability7: () => AsyncIterator<number> = async function * () {
@@ -210,10 +189,9 @@ tests/cases/conformance/types/asyncGenerators/types.asyncGenerators.es2018.2.ts(
     async function * explicitReturnType12(): Iterator<number> {
                                              ~~~~~~~~~~~~~~~~
 !!! error TS2322: Type 'AsyncGenerator<number, any, undefined>' is not assignable to type 'Iterator<number, any, undefined>'.
-!!! error TS2322:   Types of property 'next' are incompatible.
-!!! error TS2322:     Type '(...args: [] | [undefined]) => Promise<IteratorResult<number, any>>' is not assignable to type '(...args: [] | [undefined]) => IteratorResult<number, any>'.
-!!! error TS2322:       Type 'Promise<IteratorResult<number, any>>' is not assignable to type 'IteratorResult<number, any>'.
-!!! error TS2322:         Property 'value' is missing in type 'Promise<IteratorResult<number, any>>' but required in type 'IteratorYieldResult<number>'.
+!!! error TS2322:   The types returned by 'next(...)' are incompatible between these types.
+!!! error TS2322:     Type 'Promise<IteratorResult<number, any>>' is not assignable to type 'IteratorResult<number, any>'.
+!!! error TS2322:       Property 'value' is missing in type 'Promise<IteratorResult<number, any>>' but required in type 'IteratorYieldResult<number>'.
 !!! related TS2728 /.ts/lib.es2015.iterable.d.ts:33:5: 'value' is declared here.
         yield 1;
     }
diff --git a/tests/cases/compiler/deeplyNestedAssignabilityErrorsCombined.ts b/tests/cases/compiler/deeplyNestedAssignabilityErrorsCombined.ts
new file mode 100644
index 00000000000..d802c707830
--- /dev/null
+++ b/tests/cases/compiler/deeplyNestedAssignabilityErrorsCombined.ts
@@ -0,0 +1,15 @@
+let x = { a: { b: { c: { d: { e: { f() { return { g: "hello" }; } } } } } } };
+let y = { a: { b: { c: { d: { e: { f() { return { g: 12345 }; } } } } } } };
+x = y;
+
+class Ctor1 {
+    g = "ok"
+}
+
+class Ctor2 {
+    g = 12;
+}
+
+let x2 = { a: { b: { c: { d: { e: { f: Ctor1 } } } } } };
+let y2 = { a: { b: { c: { d: { e: { f: Ctor2 } } } } } };
+x2 = y2;
\ No newline at end of file
diff --git a/tests/cases/compiler/nestedCallbackErrorNotFlattened.ts b/tests/cases/compiler/nestedCallbackErrorNotFlattened.ts
new file mode 100644
index 00000000000..76a1fabdf6e
--- /dev/null
+++ b/tests/cases/compiler/nestedCallbackErrorNotFlattened.ts
@@ -0,0 +1,7 @@
+// @strict: true
+type Cb<T> = {noAlias: () => T}["noAlias"]; // `"noAlias"` here prevents an alias symbol from being made
+// which means the comparison will definitely be structural, rather than by variance
+
+declare const x: Cb<Cb<Cb<Cb<number>>>>; // one more layer of `Cb` adn we'd get a `true` from the deeply-nested symbol check
+declare let y: Cb<Cb<Cb<Cb<string>>>>;
+y = x;
\ No newline at end of file