Hi, I have the same pb. on my ubuntu xenial, here's what I get in the "lightdm.service" journal :
$ journalctl -au lightdm -S "2020-01-29 1:59" -- Logs begin at lun. 2020-01-27 11:14:43 CET, end at mer. 2020-01-29 02:01:47 CET. -- janv. 29 01:59:45 sebastien-B206 lightdm[11808]: Failed to write utmpx: Permission denied janv. 29 01:59:45 sebastien-B206 lightdm[11808]: Error writing to daemon: Bad file descriptor janv. 29 01:59:45 sebastien-B206 lightdm[11808]: Error writing to daemon: Bad file descriptor janv. 29 01:59:45 sebastien-B206 lightdm[11808]: Error writing to daemon: Bad file descriptor janv. 29 01:59:45 sebastien-B206 lightdm[11808]: Failed to write utmpx: Permission denied -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to lightdm in Ubuntu. https://bugs.launchpad.net/bugs/1782510 Title: lightdm automatically logs in after logout Status in GNOME Keyring: New Status in Light Display Manager: New Status in skype: New Status in lightdm package in Ubuntu: Confirmed Bug description: Lightdm makes it impossible to logout. After I logout the lightdm logs me automatically backs in. ProblemType: Bug DistroRelease: Ubuntu 16.04 Package: lightdm 1.18.1-0ubuntu1 ProcVersionSignature: Ubuntu 4.4.0-130.156-generic 4.4.134 Uname: Linux 4.4.0-130-generic x86_64 NonfreeKernelModules: nvidia_uvm nvidia_drm nvidia_modeset nvidia ApportVersion: 2.20.1-0ubuntu2.18 Architecture: amd64 CurrentDesktop: KDE Date: Thu Jul 19 01:18:52 2018 InstallationDate: Installed on 2016-04-26 (814 days ago) InstallationMedia: Ubuntu-Server 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.3) SourcePackage: lightdm UpgradeStatus: No upgrade log present (probably fresh install) To manage notifications about this bug go to: https://bugs.launchpad.net/gnome-keyring/+bug/1782510/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : [email protected] Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp

