diff --git a/src/server/trace/recorder/tracing.ts b/src/server/trace/recorder/tracing.ts
index 86058bb2f0..11febc57e4 100644
--- a/src/server/trace/recorder/tracing.ts
+++ b/src/server/trace/recorder/tracing.ts
@@ -38,7 +38,7 @@ export type TracerOptions = {
   screenshots?: boolean;
 };
 
-export const VERSION = 2;
+export const VERSION = 3;
 
 type RecordingState = {
   options: TracerOptions,
diff --git a/src/server/trace/viewer/traceModel.ts b/src/server/trace/viewer/traceModel.ts
index e463c816d0..bf960821c0 100644
--- a/src/server/trace/viewer/traceModel.ts
+++ b/src/server/trace/viewer/traceModel.ts
@@ -130,6 +130,32 @@ export class TraceModel {
     }
     return event;
   }
+
+  _modernize_2_to_3(event: any): any {
+    if (event.type === 'resource-snapshot' && !event.snapshot.request) {
+      // Migrate from old ResourceSnapshot to new har entry format.
+      const resource = event.snapshot;
+      event.snapshot = {
+        _frameref: resource.frameId,
+        request: {
+          url: resource.url,
+          method: resource.method,
+          headers: resource.requestHeaders,
+          postData: resource.requestSha1 ? { _sha1: resource.requestSha1 } : undefined,
+        },
+        response: {
+          status: resource.status,
+          headers: resource.responseHeaders,
+          content: {
+            mimeType: resource.contentType,
+            _sha1: resource.responseSha1,
+          },
+        },
+        _monotonicTime: resource.timestamp,
+      };
+    }
+    return event;
+  }
 }
 
 export type ContextEntry = {
diff --git a/src/server/trace/viewer/traceViewer.ts b/src/server/trace/viewer/traceViewer.ts
index bcaf342d6c..18e618187e 100644
--- a/src/server/trace/viewer/traceViewer.ts
+++ b/src/server/trace/viewer/traceViewer.ts
@@ -83,7 +83,8 @@ export class TraceViewer {
         const networkFile = path.join(tracesDir, (match ? match[1] : debugName) + '.network');
         const model = new TraceModel(snapshotStorage);
         await appendTraceEvents(model, traceFile);
-        await appendTraceEvents(model, networkFile);
+        if (fs.existsSync(networkFile))
+          await appendTraceEvents(model, networkFile);
         model.build();
         response.end(JSON.stringify(model.contextEntry));
       })().catch(e => console.error(e));