When trying to add this user to this programme as a facilitator, an on-screen message pops-up informing me that
There was an error: Sorry, Monika Wolting is not an existing user.
She most certainly is an existing user.
It's pretty urgent, as the project is on-going and the user really is an on-campus professor running the course.
Shani informed me that she's been having similar problems adding some users as participants.
The dashboard verifies users by checking for a global account on the central login wiki, Meta. That user is not connected on Meta: https://meta.wikimedia.org/wiki/User:Monika_Wolting
She should log in, then visit Meta. After that, it should work. (This only affects older accounts that have never visited Meta, like this one created in 2014. New accounts are always connected to Meta now.)
@Ragesoss Ok then, any chance to fix that? It affects ordinary editors as well: User:Lukasoch @ pl.wikipedia. Can't add him as editor ("Lukasoch: failure — Not an existing user."), because apparently he registered back in 2011. Contacting him and explaining who I am, what Meta is, why exactly do I want him to edit anything there... It would take a lot of effort just to add his username to Dashboard. There must be a better way to do it. Like, remove the whole meta check?
Checking for whether the user exists is essential, because otherwise there will be many unnoticed typos and it won't be collecting the data that people expect.
A possible solution would be to fall back to the home wiki of the program for users who don't have accounts on Meta. I'll add this to the issue list.
That turned out to be pretty easy. @Halibutt: it should work for adding those users now.