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Compatibility with PHP 7.4

Hi Air,

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.

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):

Would you recommend to switch back to PHP 7.3 or should I better stay with PHP 7.4 and continue montoring?
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  • AirAir
    Posts: 10,965
    Hey :-)

    I am not aware of any issues withe the theme and PHP 7.4, but I can not rule out such possibility.

    As for your site being test subject for PHP 7.4 - if you are facing notices, and some issues, I would switch back to 7.3 as it is still the second best choice. Wait some time, maybe a month, and try to switch to 7.4 again. Maybe till that time software author will upgrade their products for better compatibility.

    With kind regards.
  • Posts: 89
    Hi Air,

    okay, thanks very much for your help.

    Will switch back to PHP 7.3 now. Have kept PHP 7.4 for one month, but there are still error notices in the in WP Debug logs. I'm using latest updates. See attached screenshot from today's log.

    Will report out what (and if at all) will be logged with PHP 7.3

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  • edited March 2020 Posts: 89
    Brief update!

    Since having downgraded to PHP 7.3 there are no further logs in WP Debug. Thus the issues are definitely related to PHP 7.4.

    The access problem as described in early Feb seems to be gone.
    Post edited by MLG76 on
  • AirAir
    Posts: 10,965
    Hey :-)

    I hope you are healthy and safe :-)

    As for those notice, they doesn't seem to be easy to hunt down as they are very vague.

    They also seem to be connected to WP CLI, which I don't use at all.

    Good news are, that notices don't stop your site from working, but I will keep my eyes open.

    WIth kind regards.
  • Posts: 110
    I using PHP 7.4.5 and everything work fine. If have Cpanel and PHP selector try reset to Defaults modules
  • Posts: 89
    @robi052 Thanks for sharing your experience. I will try this and report out.
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