This strange issue suddenly appeared out of nowhere where I can't install/update/remove any of the extensions through the admin panel. Doing any of that displays a 404 page!
Even when I try to customize the theme through WordPress I get a 404 as well. :(
I have no idea what's going on. I don't remember doing anything to the site before this showed up, and the files that return a 404 are actually there.
By the way, this happened after one of the extensions (Yet Another Related Posts Plugin) showed this error:
Fatal error: Cannot access parent:: when current class scope has no parent in <path>/yet-another-related-posts-plugin/class-cache.php on line 466
- Saving permalink structure
- Disabling all plugins
- Temporarily removing .htaccess
Could it be a server-side thing that the host did?