Start URL responds with a 200 when offline

If Lighthouse does not receive an HTTP 200 response when accessing a page from the start_url, then either the start_url isn't correct, or ths page is not accessible offline (see also What is network reliability and how do you measure it?). Lighthouse flags web apps when the start URL doesn't respond with a 200 when offline

Lighthouse audit showing start URL doesn't respond with 200 when offline
Fig. 1 — Start URL doesn't respond with 200 when offline

Recommendations

  1. Check that the start_url in your manifest is correct Add a web app manifest.
  2. Add a service worker to your app.
  3. Use the service worker to cache files locally.
  4. When offline, use the service worker as a network proxy to return the locally cached version of the file.

Use what you learn in this step-by-step, hands-on codelab to learn how to add a service worker into your own app.

Codelabs

See it in action
Learn more and put this guide into action.

Learn more in Current page responds with a 200 when offline.

Each PWA audit is weighted equally in the Lighthouse PWA Score, with the exception of three manual audits: Site works cross-browser, Page transitions don't feel like they block on the network, Each page has a URL. Learn more in The Progressive Web App score.

More information

Start URL doesn't respond with 200 when offline audit source

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