I have explored all solutions proposed on the thread you shared, all the patches proposed seem to be already applied in my core files (I didn't check the mySql files since it's not my case, obviously).
I also checked the tables views and sequences in my database, all have the same owner (so it's not the origin of the problem)
It's "uid"
Only the "uid" one
The keys I see for the "users" table are :
- uid
- uuid
- langcode
I agree that they must be some differences that cause this problem, but as for steps to reproduce I can't give others (this is all that I did).
Maybe there was something in the old site structure that can cause this problem ?
pkimmel → created an issue.