☂ "Unable to load the page"

Within Lighthouse, this error comes from `gatherRunner.assertPageLoaded`. This is called right after we finish loading the page for a pass (there are 3 passes by default). It looks for the HTML resources's network record (via some URL comparison).

If it fails to find a match, we error. Or if we find a match, but the network record is marked as `failed`, then we error.

There are a few cases in which this error shows up.

1. **Server failure with initial request URL:** The HTML request was matched but determined to be failed. This happens with incorrect server configurations, when the server does not reply at all, or replies with an empty/otherwise invalid response. Examples: #2459 (redirect configuration was botched, resulting in a error page if you navigate to the HTTP regularly in chrome) #2500 (TLS handshake error) #2646 (a local server replies with an empty response)
**Solution:** Fix your server to return valid HTML documents with successful status codes.
1. **Server doesn't offer HTTP:** The host doesn't offer a site at the HTTP URL at all. Example: #1978
**Solution:** Change your server to redirect HTTP traffic to HTTPS
1. ~**HSTS:** The host is using HSTS, and Chrome can't allow the browser to attempt to navigate to HTTP. Example: #2465~
1. **about:blank:** Audits was started on about:blank somehow. Canonical issue: #2362. This *should* be [fixed](https://github.com/ChromeDevTools/devtools-frontend/commit/a3b3d85785aee95f86b489c81bc8a63c1f011dcb) on the DevTools side, and will ship in m61, but can still happen occasionally for unknown reasons. If this happens *consistently* on a particular URL for you, please file a separate issue specifying the URL.
**Solution:** Restart Chrome and run Lighthouse again. If problem persists with a particular URL, file a new issue here with the title "Reproducible about:blank errors"
1. **No document request found:** Lighthouse was unable to identify any network request as the main HTML resource. Example: #3496
**Solution:** Restart Chrome and run Lighthouse again. If problem persists with a particular URL, file a separate issue with the title "Cannot identify main document"
1. **Bad TLS/certificate interstitial.** Lighthouse couldn't load the page because Chrome couldn't handle the security configuration of the URL. Example #1123
**Solution:** Fix your server to return a valid, secure TLS certificate.