This defect may not be in lightdm package. I was just able to reproduce it on Ubuntu 18.04.01 distribution. Here is how I did it.
I am using 18.04.01 with KDE. I installed the skypeforlinux package This package had unsatisfied dependency gnome-keyring as without it skype will not log in automatically. I installed gnome-keyring and seahorse so that I can reset the keyring. After these three I wasn't able to logout from my KDE session as I was logged back in. It didn't help to uninstall skypeforlinux or seahorse. Only after I uninstalled gnome-keyring and restarted my computer I am able to normally logout from my KDE session. On a side node now even after I log out, I can still see my session hanging around using sudo loginctl If I log in it till create second session as reported by the above command but at least I can logout reliably. ** Also affects: lightdm Importance: Undecided Status: New ** Also affects: gnome-keyring Importance: Undecided Status: New ** Also affects: skype Importance: Undecided Status: New -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1782510 Title: lightdm automatically logs in after logout To manage notifications about this bug go to: https://bugs.launchpad.net/gnome-keyring/+bug/1782510/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs