I use MediaWiki for a private single user purpose in a cPanel managed commercial host, and used its upgrade mechanism to upgrade from 1.37.6 to 1.39.1. Before upgrade and after upgrade I was able to log into MW. However, there was a problem with one page, and I decided to revert to the complete backup of 1.37.6 cPanel had made for me to see if it worked there.
After this, I was not able to log in any more. I tried also to create a new user, and it succeeded partly - a new user was created, but the username I gave was not registered in the mySQL database, while my full name was, and after I logged out, there was no way to log back in.
Also, cPanel sets the wiki admin user name and password, and these did not work either anymore, and setting it again and saving through cPanel has no effect on the MW. I tried to upgrade to 1.39.1 again, and the same situation continues.
I am able to browse the mySQL with cPanel, and I see e.g. the user I created in mw_user as "Unknown user", but with my name as the "Full name". This unknown user is the only row in the mw_user table. My former two users (admin and normal) are visible in the mw_actor table.
Any ideas?