The bits that actually run the site, which is all written in PHP, have a bunch of accelerators, caching units and things.
I'm trying to get the site from PHP7 to PHP8. I got 95% of it working last night, but that last 5% is a killer so had to take a backup of my work; restore my previous backup of the accelerators and get the site back online.
I'll flip back to the new image at some point maybe tonight and have another go. I remember the exact same issue was a killer when I moved the hosting to its current setup. Exactly the same error. And I fixed it by doing ......
? NFI.
But if I can get this last issue resolved everything is on fully supported LTS Linux images so should be good for the life of the site, basically. Because I'll probably never do this work again