Login problem for specific user - blacklisted?

I am using 28.01. on debian bookworm, apache 2.4.57, some 10 users directly stored in mariadb-10.11.4.

I have a problem with one specific user who isn’t able to log in.

I reset his passwort, so it is correct. His real name has German special chars in it. I use ascii expressions for those in the login name. I have some other users where I do the same - everybody is fine.

What’s strange is that he is listed at the bottom of my users list, though in alphabetic order he should be somewhere in the middle.

When he tries to log in, the log shows the following:

—cut—
“user”:“–”,“app”:“no app in context”,“method”:“POST”,“url”:“/nextcloud/login”,
—cut—

where the real names are looged when everybody else logs in, like:

“user”:“SurnameName”,“app”:…

It “feels” like I put this name on some kind of “blacklist”, but I can’t remember that I did so. However, the problem might exist for quite some time now. He isn’t a very excessive user of my cloud.[1]

I already had a look at the user table in the database (adminer), but nothing obvious for me.

Any hint appreciated. TIA.

[1]
Yes, I can most likely delete him, create a new account and even transfer the data, but I would definately prefer to find the root of evil.

Did you list all user related entries from the database to enable comparison?

Here some tables you could compare:
oc_accounts, oc_accounts_data, oc_users

SELECT * FROM $table

and (replace $userid with the login name of the user)

SELECT * FROM oc_preferences WHERE userid = "$userid" and appid IN ('core', 'settings', 'login');

Maybe something will immediately catch your eye.

Much luck,
ernolf

Thanks. Tried that but nothing obvious :(. In the end I deleted the user, created him again and restored data. Everything fine again and working, however, he is still at the bootim of the users list:

So still somewhat strange :(.