We have a wordpress-blog running on version 6.1.6. The PHP version on our hosting server is 8.1.27. I know that the WP version is quite old. We bought the website over a year ago and now wanted to update it before we make changes to it.

So… we set a up a testing site (works perfectly) to make changes and updates before applying them to the main site. Our theme uses X and is a child theme of it.

I knew, that this would probably cause some problems when updating wordpress. So I deactivated every plugin and change the theme to the wp standard theme 2022. We also tried updating it before with the custom theme, but we only got white screens or other errors like cant reach site etc.
Sadly, also when we try to update our WP without any plugin or custom theme, we get the following message:

You website has a critical error. (message from wordpress itself)

And after reloading:

The server is temporarily unable to service your request due to maintenance downtime or capacity problems. Please try again later.

WordPress says that the update was successful, but the site is gone. Of course we have backups. For some reason though, there is no debug.log file created. Debug and Debug log is set to true.

We’ve tried to update wordpress with plugins on, plugins of, custom theme on and off and so on. We’ve also tried launching it locally via MAMP on PHP 8.2.0, but it didn’t work. The site was loading and you could the fragments of the blog, but it said that the website doesn’t exist anymore or has never existed.