What has occurred is due to the change of UID_MIN AccountsService has decided that your existing user (501) is now a system user. GDM has then decided that there are no user accounts on the system, so has triggered gnome-initial-setup to create one.
I suspect if you had rebooted after changing UID_MIN back it would have worked fine (user showed in GDM, gnome-initial-setup not run). I'll assign this to the 'login' package which has decided to change the MIN_UID to 1000 - it may be this is an issue on older systems that used to have this value. ** Package changed: gnome-initial-setup (Ubuntu) => shadow (Ubuntu) ** Summary changed: - gnome-initial-setup prevents me from logging in with my existing user (UID 501) + Login package changes MIN_UID in /etc/login.defs -> AccountsService/GDM then ignores existing user (UID 501) -> starts gnome-inital-setup to create user -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1770233 Title: Login package changes MIN_UID in /etc/login.defs -> AccountsService/GDM then ignores existing user (UID 501) -> starts gnome-inital-setup to create user To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/shadow/+bug/1770233/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs