Lighthouse: Speed Index - Invalid score for speed-index: NaN

Question

Does anyone know what this error even means? It is non-descript does not really lend itself to a debugging path. This occurs when testing page speed in google Lighthouse.

Answer 1

Facing the same issue and raised to the lighthouse Github repo.

Refer: https://github.com/GoogleChrome/lighthouse/issues/11173

They are able to reproduce it and will be fixing this soon as part of this ticket: https://github.com/GoogleChrome/lighthouse/issues/11154

Answer 2

Could be a variety of factors. Post the URL along with the question - easier to debug.

1. Speed index - has a blocker, if anything takes more than 10secs, LightHouse will time-out.

2. If you are using CDN - I have experience sporadic errors on LightSpeed due to cache consistency issues.

3. Make sure there are no blockers on your site, and you run this on a new/private window. No browser extensions should be enabled.

4. LightHouse uses the same underlying API. Try using PSI - https://developers.google.com/speed/pagespeed/insights/. Also, try the web version of lightspeed: https://web.dev/measure/. If you get same results - something on your end. If you get different results, something with your browser/ test.

5. Try running LightHouse on Mobile and Desktop.