PHP 8.4-FPM Causes Random 502 Errors on WordPress WooCommerce Admin Pages

Virtualmin
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SYSTEM INFORMATION
OS type and version Debian Linux 12
Webmin version 2.303
Virtualmin version 7.30.8
Webserver version Nginx version 1.22.1
Related packages PHP 8.3 - 8.4

Hi,

I’m experiencing a strange issue on a VPS running Debian 12 (ARM64 architecture) with the following specs:

  • RAM: 24 GB (24,576 MiB)
  • CPU: 12 cores
  • Web Stack: Nginx + PHP-FPM
  • PHP Version: 8.4 stable
  • Websites: 3 WordPress websites (2 of them WooCommerce)
  • Cloudflare: Free plan (currently in Development Mode)

Issue:
After some time (without any obvious pattern), I start getting 502 errors in the browser console when trying to access: /wp-admin/admin.php?page=wc-orders

What I’ve Tried:

  • Restarting PHP 8.4-FPM using sudo service php8.4-fpm restart resolves the issue temporarily. However, after restarting, only one of the WooCommerce websites starts working correctly (normally the one that I load first), while the other one still returns 502 errors in the same admin path.
  • Restarting PHP-FPM again may cause the other site to start working while the first one breaks - so it alternates.

Downgrading to PHP 8.3 with the exact same PHP-FPM and Nginx settings resolves the issue completely.

Any idea why this occurs? Seems to be PHP 8.4 specific given that I don’t have that issue on PHP 8.3.

Worth mentioning that the logs do not show me anything relevant.

Thanks!

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You need to look at the logs. Both the web server error log and the PHP-FPM log for the domain.

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Wordpress does not support php 8.4

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And plugin need to compatible too. Says its compatible by this chart.

I just tested on one of my wordpress sites and works fine.
Turn on debug mode.

Woocommerce I would think should be able to run 8.4

Installed it and went to /wp-admin/admin.php?page=wc-orders
and no issue.

I run on apache BTW. Can you go to your site without cloudflare, maybe add the site to you PC’s host file. I think error 502 is a gateway error.
The downgrade 8.3 fix is a bit weird though.

Can you get to site health? wp-admin/site-health.php

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The obvious answer is SOMETHING doesn’t like 8.4. How much do you want to dig into it? Kinda note it in case others run into the same problem and move on? Often in these kind of threads it turns out nothing in the original post was the real culprit. Servers and web sites just have so many moving parts.

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Everyone could keep guessing, or OP could look at the logs and know.

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Hi everyone, thank you for your responses. You’re likely correct - it seems to be an issue with WordPress or one/multiple WordPress plugins not yet compatible with PHP 8.4. Since I couldn’t find any relevant logs indicating errors with nginx or PHP, I’ll stick to PHP 8.3 for now, as it’s working perfectly. I’ll wait until WordPress officially announces support for PHP 8.4 before upgrading.

1 Like