diff --git a/src/server/session.ts b/src/server/session.ts
index 7e6bca66c04..52bf905dedc 100644
--- a/src/server/session.ts
+++ b/src/server/session.ts
@@ -711,7 +711,8 @@ namespace ts.server {
                     catch { } // tslint:disable-line no-empty
                 }
 
-                if (err.message && err.message.indexOf(`Could not find sourceFile:`) !== -1) {
+                if (err.hasOwnProperty("ProgramFiles")) {
+                    msg += `\n\nProgram files: {(err as any)["ProgramFiles"]}\n`;
                     msg += `\n\nProjects::\n`;
                     let counter = 0;
                     const addProjectInfo = (project: Project) => {
diff --git a/src/services/services.ts b/src/services/services.ts
index b769ee2da3e..51987c26889 100644
--- a/src/services/services.ts
+++ b/src/services/services.ts
@@ -1158,7 +1158,12 @@ namespace ts {
         function getValidSourceFile(fileName: string): SourceFile {
             const sourceFile = program.getSourceFile(fileName);
             if (!sourceFile) {
-                throw new Error(`Could not find sourceFile: '${fileName}'.`);
+                let error = new Error(`Could not find sourceFile: '${fileName}'.`);
+
+                // Attach sidecar data for the server log
+                (error as any)["ProgramFiles"] = program && JSON.stringify(program.getSourceFiles().map(f => f.fileName));
+
+                throw error;
             }
             return sourceFile;
         }