karel0017

No, I would like to understand first how that affects the site. My understanding is that this would just exclude all pages from optimization, or am I wrong? That would not solve the root cause.

I see that another user asked the same question but had no answer yet.

Can you please explain why this would solve the issue?

I have exactly the same problem. It took me weeks before I could pin down the problem and find that it it Litespeed guets mode that is causing Pagespeed to give an error on mobile. Also mobile compatibility fails in Google when guest mode is active. When I disable Guest mode the site is mobile friendly again and pagespeed does not give “unknown error” anymore.
However: there must be a secondary element that causes this. I run another website which has guest mode ON and this problem does not appear at all.

Has a cause or solution been found?

Hi,

Your suggestion made me look at the securtity settings again. The issue has been solved by turning on and back off the hosting security setting previously changed.

Thanks!