Today I had to do some support on a Drupal 6 website and when I tried to refresh a CSS file, all the themes disappeared. When going to the theme page, nothing in the list at all. Not even the core themes.
This is a Drupal 6.x website and I am running it on my current development system which runs PHP 7.x among other things.
Why would my theme disappear like that?
Note: I tried clearly all the cache tables and click on the "Clear all Caches" and the caching is turned off in the Performance screen (so that way I know it's not that creating problems.)