If Lighthouse does not receive an HTTP 200
response when accessing a page from the
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
- Check that the
start_urlin your manifest is correct Add a web app manifest.
- Add a service worker to your app.
- Use the service worker to cache files locally.
- 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.
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.
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