This is a recurring bug with users not being able to log in, due to inconsistent state between CentralAuth and local wikis (specifically the local user table row missing in the latter).
>>! In T119736#2126728, @Florian wrote:
> Problem description: The user gets an exception whenever he tries to login and every other one get an exception when opening the CentralAuth page (of the user): https://en.wikipedia.org/wiki/Special:CentralAuth/USERNAME
====For user which this affects
A possible fix: Enter your username at [[https://test.wikipedia.org/wiki/Special:CentralAuth|testwiki:Special:CentralAuth]]. Look for text of form `Could not find local user data for username@X`, where `username` is your name and `X` is the name of a wiki. Try to log in at that wiki. For example, if `X` is `bewiki` then enter `be:` in the search box to get to the [[https://be.wikipedia.org/wiki/|be:]] wiki, or look for the wiki at [[https://en.wikipedia.org/wiki/Special:SiteMatrix|Special:SiteMatrix]]. The language may be foreign but the login link should be at the top right or top left, or you can enter `Special:UserLogin` in the search box.
This description was edited to reflect the actual issue, and not only about the first affected users situation. ~@Josve05a