Error google pagespeed insight analyst: Lighthouse returner error: Non html, specified page is not helm (published as type MIME), how to fix?


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May I ask which URL have you entered into the input field to test or you runned it via an Web Browser extension like for Google Chrome?

May I ask have you got HTTP/2 Early Hints enabled at Cloudflare?

Lighthouse has a bug that is triggered because of some feature the web server uses.

Currently (March 2021) Lighthouse on Google PageSpeed Insights seems to have a bug that produces NOT_HTML in some constellations when HTTP/2 Early Hints are activated in the web server. I’ve had a similar problem today and found that disabling H2EarlyHints in Apache 2.4.46 prevented the issue.

This could be the Google issue:

Possible trails to troubleshoot here:

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