Thread:Project:Support desk/Upgrade from MW 1.18.1 to 1.23.5 broke sysop and Bureaucrat users functionality/reply (6)

Alright, the problem then was not that the (old) usernames did no longer have the right permissions, but that you in fact got logged in with a different username and this user had a different ID in the user table and so did not get the permissions assigned. Sounds to me like something was changed in the (external?) login mechanism you are using.