changed from PHP 7.3 to 7.4 last week.
I'm wondering if there are any known compatibility issues.
I'm asking, as since then, there is one severe issue. Sporadicly once you try to enter the website, there is a bad routing I haven't yet traced down its reason. The URL looks weird (compare screenshots). This happened from various clients from various locations. It also isn't a caching problem, as most clients called up the website initially.
This I've contacted my hosts (raidboxes) support. They provided me the third attached screenshot. Good news: In general everything looks fine. No serious issues in their reports. But they also noticed these referrer incidents. However, they couldn't tell me what's wrong and blamed plugins, mainly Polylang as candidate to investigate, as that alters referrers.
I told them that things had been running absolutely stable and there wasn't any change, except PHP 7.3 to 7.4.
Interesting also: Upon clicking to the language logo of Polylang, the site was loading properly. The problem only occurred if you tried to access via a the main root domain (e. g. lange-grumfeld.photo).
Well, we agreed to start WP Debug log, to trace the problem.
Since doing so, the following results came out (see fourth screenshot). There are some entries I'm struggeling to interpretive and - believe it or not - our old friend the CLI is back (at least in that report). Remember we pulled the plug on this a while ago? I don't think that has anything to do with it.
I've opened also an incident here (which obviously nobody cares about, as either my problem seems to be too stupid or unknown at all):https://wordpress.org/support/topic/php-7-4-and-polylang/
Would you recommend to switch back to PHP 7.3 or should I better stay with PHP 7.4 and continue montoring?