Hi there.
I have recently been receiving the PHP Update Recommended warning on my up-to-date Wordpress installation, and so decided to upgrade my 7.4.33 PHP version to 8.3 using OVH Manager.
This however produces a 500 Internal Server error when trying to access the site homepage or admin page: "...wp-admin/plugins.php?plugin_status=all&paged=1&s might have a temporary problem or it could have moved."
I tried deactivating all the plugins but with no change. I then installed theme Twenty twenty-five and activated that rather than the older theme I normally use, again with no change.
Does anybody have an idea about what the issue might be?
6136 
27.11.2025 17:35
Hello,
Please set your PHP environment in "development" mode.
Doing so, your error messages should be more verbose. This may direct to the culprit.
Finally, upgrade your Wordpress using this official method : https://developer.wordpress.org/advanced-administration/upgrade/upgrading/
Hello,
Please set your PHP environment in "development" mode.
Doing so, your error messages should be more verbose. This may direct to the culprit.
Finally, upgrade your Wordpress using this official method : https://developer.wordpress.org/advanced-administration/upgrade/upgrading/
Hello fritz2cat,
Many thanks indeed. I set the PHP to Development mode and the resultant message indicated that the problem lay in my wp-config.php file, namely the line:
define('WP_AUTO_UPDATE_CORE', minor);
which needed minor to be in quotes.
It makes sense since wp-config.php, being user-specific, is not normally updated, and I can only assume that earlier versions of PHP when encountering a previously-unknown variable value, treated it as a literal constant as a fallback.
The site is now running under 8.4 and you deserve my sincere appreciation. Thanks!
One small issue however, which is a bit perplexing. When I go into the editor to edit a page (using Classic Editor & Advanced Editor Tools) under 8.4 or 8.3, the toolbar of edit buttons (bold, italic etc) doesn't show, the Add Media button doesn't work, and the Preview Changes button doesn't show any edits since the last update. I'm forced to go back to 7.3 to get these to work ok. I've tried clearing caches to no avail.
Do you have any idea what may be causing this or would it be better to post this issue on a Wordpress forum?
Hi,
IMO you should better ask in a WP forum. Did you overwrite the Wordpress files from a zip file, as suggested above ?
Hi there. No, I didn't because I didn't need to get that far. By a process of plugin isolation, I figured out that one of my plugins was causing the issue. It was outdated, not having received updates for quite a while, and was using some now-retired PHP calls (security-wise it was probably outdated too). I deleted the plugin and found a replacement, more up-to-date, plugin that achieves the same purposes, so all is good now.
Many thanks indeed for your great help with this! I have a working system and I've learned a lot so that's a bonus too.
Hello@Pete ,
Did you reply this morning (4 Sep) ?
I have received a notification with this link: https://community.ovhcloud.com/community?id=community_question&sys_id=3a868ae0453362142d4c20f5954d721c&anchor=answer_b619de0dedb7eed02d4c1401eeffb610
but your reply cannot be found.
The 500 error occurs because WordPress, a plugin, or theme isn’t fully compatible with PHP 8.3.
Check error logs or enable WP_DEBUG to identify the exact issue.
Ensure all plugins, themes, and required PHP extensions are updated or revert PHP temporarily.