One user can log in the rest can't.
 

I installed 18.3 and created users for me and my kids. I can log in, kids can't -- after them entering their respective passwords the screen turns black for about 2 seconds, then the login screen comes back. No error message. Google didn't help. Any ideas here?

Permissions on their home directories would be the first place to check. If they're not owned and/or read/writeable to their respective user ID's, they can't create the necessary files/directories that KDE/Gnome/Whatever-DE is going to want to create.

Iwill try that, when I come home. What is the mechanism mint uses to connect users to their home directories? Is it the username, a user-ID (like 1001) and how can one check or change that "connection"?

When you create the user, it will either create the home directories (read the man page on the useradd command), or not. If it doesn't...that means you have to create them manually. Such information is tied both to user name and ID. Look at an entry in the /etc/passwd file to see what it looks like.

Easiest to delete the few users you created, and re-add them with the "-m" flag, and specify their home directories. Will automatically get created with proper permissions and skeleton files.

Okay. I'll read the man page and look at /etc/passwd.



Here the problem is, that these directories exist on an extra partition and hold some data from a former installation of 17.3. I want to keep and re-use them. Never had this problem before ... :scratch:.

Gah. Solved. And so easy, thanks TB0ne: The user:group values of my children just were exchanged (son <-> daughter), simply "chown -R <son>:<son> /home/<son> or daughter as it is and all is well. Thread marked as solved. There are situations or days when one is simply dense, it seems. Thanks again.