diff --git a/lighthouse-core/lib/proto-preprocessor.js b/lighthouse-core/lib/proto-preprocessor.js
index a23d1d660877..721a488d1d34 100644
--- a/lighthouse-core/lib/proto-preprocessor.js
+++ b/lighthouse-core/lib/proto-preprocessor.js
@@ -32,6 +32,11 @@ function processForProto(result) {
     }
   }
 
+  // Remove runtimeError if it is NO_ERROR
+  if (reportJson.runtimeError && reportJson.runtimeError.code === 'NO_ERROR') {
+    delete reportJson.runtimeError;
+  }
+
   // Clean up actions that require 'audits' to exist
   if (reportJson.audits) {
     Object.keys(reportJson.audits).forEach(auditName => {
diff --git a/lighthouse-core/test/lib/proto-preprocessor-test.js b/lighthouse-core/test/lib/proto-preprocessor-test.js
index b35982970117..cadb0a455545 100644
--- a/lighthouse-core/test/lib/proto-preprocessor-test.js
+++ b/lighthouse-core/test/lib/proto-preprocessor-test.js
@@ -27,6 +27,30 @@ describe('processing for proto', () => {
     expect(JSON.parse(output)).toMatchObject(expectation);
   });
 
+  it('cleans up default runtimeErrors', () => {
+    const input = {
+      'runtimeError': {
+        'code': 'NO_ERROR',
+      },
+    };
+
+    const output = processForProto(JSON.stringify(input));
+
+    expect(JSON.parse(output)).not.toHaveProperty('runtimeError');
+  });
+
+  it('non-default runtimeErrors are untouched', () => {
+    const input = {
+      'runtimeError': {
+        'code': 'ERROR_NO_DOCUMENT_REQUEST',
+      },
+    };
+
+    const output = processForProto(JSON.stringify(input));
+
+    expect(JSON.parse(output)).toMatchObject(input);
+  });
+
   it('cleans up audits', () => {
     const input = {
       'audits': {
diff --git a/proto/lighthouse-result.proto b/proto/lighthouse-result.proto
index 7e8ba733246a..c88d8e4ce2a5 100644
--- a/proto/lighthouse-result.proto
+++ b/proto/lighthouse-result.proto
@@ -6,42 +6,41 @@ import "google/protobuf/wrappers.proto";
 
 // Canonical list of errors created by Lighthouse.
 enum LighthouseError {
-  UNDEFINED = 0;
   // No error in Lighthouse; the results are reliable.
-  NO_ERROR = 1;
+  NO_ERROR = 0;
   // An uncategorized error occurred, likely a JavaScript exception.
-  UNKNOWN_ERROR = 2;
+  UNKNOWN_ERROR = 1;
   // The trace did not contain any screenshot events.
-  NO_SPEEDLINE_FRAMES = 3;
+  NO_SPEEDLINE_FRAMES = 2;
   // No visual change between the beginning and end of load.
-  SPEEDINDEX_OF_ZERO = 4;
+  SPEEDINDEX_OF_ZERO = 3;
   // The trace did not contain any screenshot events.
-  NO_SCREENSHOTS = 5;
+  NO_SCREENSHOTS = 4;
   // The computed speedindex results are non-finite.
-  INVALID_SPEEDLINE = 6;
+  INVALID_SPEEDLINE = 5;
   // The trace did not contain a TracingStartedInPage event.
-  NO_TRACING_STARTED = 7;
+  NO_TRACING_STARTED = 6;
   // The trace did not contain a navigationStart event.
-  NO_NAVSTART = 8;
+  NO_NAVSTART = 7;
   // The trace did not contain a firstContentfulPaint event.
-  NO_FCP = 9;
+  NO_FCP = 8;
   // The trace did not contain a domContentLoaded event.
-  NO_DCL = 10;
+  NO_DCL = 9;
   // No network request could be identified as the primary HTML document.
-  NO_DOCUMENT_REQUEST = 11;
+  NO_DOCUMENT_REQUEST = 10;
   // The HTML document's network request failed due to Chrome-internal reasons
   // (canceled, blocked, etc).
-  FAILED_DOCUMENT_REQUEST = 12;
+  FAILED_DOCUMENT_REQUEST = 11;
   // The HTML document's network request completed, but returned an HTTP status
   // code of 4xx or 5xx.
-  ERRORED_DOCUMENT_REQUEST = 13;
+  ERRORED_DOCUMENT_REQUEST = 12;
   // Chromium's tracing controller did not manage to begin tracing across
   // processes. Typically fixed by restarting Chromium.
-  TRACING_ALREADY_STARTED = 14;
+  TRACING_ALREADY_STARTED = 13;
   // The trace data wasn't parsed correctly.
-  PARSING_PROBLEM = 15;
+  PARSING_PROBLEM = 14;
   // The trace data failed to stream over the protocol.
-  READ_FAILED = 16;
+  READ_FAILED = 15;
 }
 
 // The overarching Lighthouse Response object (LHR)
diff --git a/proto/sample_v2_round_trip.json b/proto/sample_v2_round_trip.json
index 8542cf721077..37b142e56882 100644
--- a/proto/sample_v2_round_trip.json
+++ b/proto/sample_v2_round_trip.json
@@ -3291,8 +3291,5 @@
     "lighthouseVersion": "3.2.0", 
     "requestedUrl": "http://localhost:10200/dobetterweb/dbw_tester.html", 
     "runWarnings": [], 
-    "runtimeError": {
-        "code": "NO_ERROR"
-    }, 
     "userAgent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/66.0.3358.0 Safari/537.36"
 }
\ No newline at end of file