The system boots up normally, and I log in. I open an xterm and this happens:
$ groups
rphelps
$ su rphelps
Password:
$ groups
rphelps adm cdrom sudo dip www-data plugdev lpadmin sambashare kismet docker
If I log in via SSH, my groups are set correctly. If I log into a tty instead of X, my groups are set correctly.
When I try to log out of the X session or hit Ctrl+Alt+L, it closes the session, but then it seems like the greeter can't be (re)started, or the lockscreen doesn't work, and it brings me back to my desktop.
I was recently mucking around with screen savers (xscreensaver, gnome-screensaver, etc.) trying to get the screen to lock after 30 minutes (no luck). Did purging those have remove something vital for logging out?
I haven't modified any /etc/ files manually.
Xubuntu 18.04
Edit 1:
$ journalctl -u lightdm.service
-- Reboot --
Jul 25 11:21:01 rphelps-DELL systemd[1]: Starting Light Display Manager...
Jul 25 11:21:01 rphelps-DELL lightdm[993]: Seat type 'xlocal' is deprecated, use 'type=local' instead
Jul 25 11:21:01 rphelps-DELL systemd[1]: Started Light Display Manager.
Jul 25 11:21:02 rphelps-DELL lightdm[1179]: pam_kwallet(lightdm-greeter:setcred): (null): pam_sm_setcred
Jul 25 11:21:02 rphelps-DELL lightdm[1179]: pam_kwallet5(lightdm-greeter:setcred): (null): pam_sm_setcred
Jul 25 11:21:02 rphelps-DELL lightdm[1179]: pam_unix(lightdm-greeter:session): session opened for user lightdm by (uid=0)
Jul 25 11:21:03 rphelps-DELL lightdm[1179]: pam_kwallet(lightdm-greeter:session): (null): pam_sm_open_session
Jul 25 11:21:03 rphelps-DELL lightdm[1179]: pam_kwallet(lightdm-greeter:session): pam_kwallet: open_session called without kwallet_key
Jul 25 11:21:03 rphelps-DELL lightdm[1179]: pam_kwallet5(lightdm-greeter:session): (null): pam_sm_open_session
Jul 25 11:21:03 rphelps-DELL lightdm[1179]: pam_kwallet5(lightdm-greeter:session): pam_kwallet5: open_session called without kwallet5_key
Jul 25 11:21:03 rphelps-DELL lightdm[1854]: pam_succeed_if(lightdm:auth): incomplete condition detected
Jul 25 11:22:37 rphelps-DELL lightdm[1854]: pam_kwallet(lightdm:auth): (null): pam_sm_authenticate
Jul 25 11:22:37 rphelps-DELL lightdm[1854]: pam_kwallet5(lightdm:auth): (null): pam_sm_authenticate
Jul 25 11:22:37 rphelps-DELL lightdm[1854]: pam_kwallet(lightdm:setcred): pam_kwallet: pam_sm_setcred
Jul 25 11:22:37 rphelps-DELL lightdm[1854]: pam_kwallet5(lightdm:setcred): pam_kwallet5: pam_sm_setcred
Jul 25 11:22:37 rphelps-DELL lightdm[1854]: pam_unix(lightdm:session): session opened for user rphelps by (uid=0)
Jul 25 11:22:37 rphelps-DELL lightdm[1854]: pam_kwallet(lightdm:session): pam_kwallet: pam_sm_open_session
Jul 25 11:22:37 rphelps-DELL lightdm[993]: Error writing to daemon: Bad file descriptor
Jul 25 11:22:37 rphelps-DELL lightdm[993]: Failed to write utmpx: Permission denied
Jul 25 11:34:02 rphelps-DELL lightdm[993]: Failed to write utmpx: Permission denied
Jul 25 11:34:02 rphelps-DELL lightdm[993]: Error writing to daemon: Bad file descriptor
Jul 25 11:34:02 rphelps-DELL lightdm[993]: Failed to write utmpx: Permission denied
Jul 25 11:40:38 rphelps-DELL lightdm[993]: Failed to write utmpx: Permission denied
Jul 25 11:40:38 rphelps-DELL lightdm[993]: Error writing to daemon: Bad file descriptor
Jul 25 11:40:38 rphelps-DELL lightdm[993]: Failed to write utmpx: Permission denied
Jul 25 11:50:05 rphelps-DELL lightdm[993]: Failed to write utmpx: Permission denied
Jul 25 11:50:05 rphelps-DELL systemd[1]: Stopping Light Display Manager...
Jul 25 11:50:05 rphelps-DELL lightdm[993]: Error updating user /org/freedesktop/Accounts/User1000: GDBus.Error:org.freedesktop.systemd1.ShuttingDown: Refusing
Jul 25 11:50:05 rphelps-DELL lightdm[993]: seat_lock: assertion 'seat != NULL' failed
Jul 25 11:50:05 rphelps-DELL lightdm[993]: Error updating user /org/freedesktop/Accounts/User1000: GDBus.Error:org.freedesktop.systemd1.ShuttingDown: Refusing
Jul 25 11:50:05 rphelps-DELL lightdm[993]: Error updating user /org/freedesktop/Accounts/User1000: GDBus.Error:org.freedesktop.systemd1.ShuttingDown: Refusing
Jul 25 11:50:07 rphelps-DELL systemd[1]: Stopped Light Display Manager.