diff --git a/src/compiler/commandLineParser.ts b/src/compiler/commandLineParser.ts
index fbc6d8d6fea1d..3aaa217fbd09d 100644
--- a/src/compiler/commandLineParser.ts
+++ b/src/compiler/commandLineParser.ts
@@ -2361,7 +2361,7 @@ namespace ts {
             if (!host.fileExists(extendedConfigPath) && !endsWith(extendedConfigPath, Extension.Json)) {
                 extendedConfigPath = `${extendedConfigPath}.json`;
                 if (!host.fileExists(extendedConfigPath)) {
-                    errors.push(createDiagnostic(Diagnostics.File_0_does_not_exist, extendedConfig));
+                    errors.push(createDiagnostic(Diagnostics.File_0_not_found, extendedConfig));
                     return undefined;
                 }
             }
@@ -2372,7 +2372,7 @@ namespace ts {
         if (resolved.resolvedModule) {
             return resolved.resolvedModule.resolvedFileName;
         }
-        errors.push(createDiagnostic(Diagnostics.File_0_does_not_exist, extendedConfig));
+        errors.push(createDiagnostic(Diagnostics.File_0_not_found, extendedConfig));
         return undefined;
     }
 
diff --git a/src/testRunner/unittests/config/configurationExtension.ts b/src/testRunner/unittests/config/configurationExtension.ts
index 25e975c0fb208..6c1fc9522954a 100644
--- a/src/testRunner/unittests/config/configurationExtension.ts
+++ b/src/testRunner/unittests/config/configurationExtension.ts
@@ -197,13 +197,13 @@ namespace ts {
     const caseSensitiveBasePath = "/dev/";
     const caseSensitiveHost = new fakes.ParseConfigHost(createFileSystem(/*ignoreCase*/ false, caseSensitiveBasePath, "/"));
 
-    function verifyDiagnostics(actual: Diagnostic[], expected: {code: number, category: DiagnosticCategory, messageText: string}[]) {
+    function verifyDiagnostics(actual: Diagnostic[], expected: { code: number; messageText: string; }[]) {
         assert.isTrue(expected.length === actual.length, `Expected error: ${JSON.stringify(expected)}. Actual error: ${JSON.stringify(actual)}.`);
         for (let i = 0; i < actual.length; i++) {
             const actualError = actual[i];
             const expectedError = expected[i];
             assert.equal(actualError.code, expectedError.code, "Error code mismatch");
-            assert.equal(actualError.category, expectedError.category, "Category mismatch");
+            assert.equal(actualError.category, DiagnosticCategory.Error, "Category mismatch"); // Should always be error
             assert.equal(flattenDiagnosticMessageText(actualError.messageText, "\n"), expectedError.messageText);
         }
     }
@@ -246,7 +246,7 @@ namespace ts {
                 });
             }
 
-            function testFailure(name: string, entry: string, expectedDiagnostics: { code: number, category: DiagnosticCategory, messageText: string }[]) {
+            function testFailure(name: string, entry: string, expectedDiagnostics: { code: number; messageText: string; }[]) {
                 it(name, () => {
                     const parsed = getParseCommandLine(entry);
                     verifyDiagnostics(parsed.errors, expectedDiagnostics);
@@ -280,26 +280,22 @@ namespace ts {
                 testFailure("can report errors on circular imports", "circular.json", [
                     {
                         code: 18000,
-                        category: DiagnosticCategory.Error,
                         messageText: `Circularity detected while resolving configuration: ${[combinePaths(basePath, "circular.json"), combinePaths(basePath, "circular2.json"), combinePaths(basePath, "circular.json")].join(" -> ")}`
                     }
                 ]);
 
                 testFailure("can report missing configurations", "missing.json", [{
-                    code: 6096,
-                    category: DiagnosticCategory.Message,
-                    messageText: `File './missing2' does not exist.`
+                    code: 6053,
+                    messageText: `File './missing2' not found.`
                 }]);
 
                 testFailure("can report errors in extended configs", "failure.json", [{
                     code: 6114,
-                    category: DiagnosticCategory.Error,
                     messageText: `Unknown option 'excludes'. Did you mean 'exclude'?`
                 }]);
 
                 testFailure("can error when 'extends' is not a string", "extends.json", [{
                     code: 5024,
-                    category: DiagnosticCategory.Error,
                     messageText: `Compiler option 'extends' requires a value of type string.`
                 }]);