I have a similar issue on Ubuntu 20.04 with 1.30.0-0ubuntu4~20.04.1. Sometimes I enter my password, the screen goes black and I have to log in another time. Once lightdm didn't start at all.
If such issues occur I have these entries in the journal: Sep 12 20:03:10 marco-MS-5455 lightdm[1123]: pam_unix(lightdm:auth): Couldn't open /etc/securetty: No such file or directory Sep 12 20:03:12 marco-MS-5455 lightdm[1055]: pam_unix(lightdm-greeter:session): session closed for user lightdm Sep 12 20:03:12 marco-MS-5455 systemd[1]: lightdm.service: Main process exited, code=exited, status=1/FAILURE Sep 12 20:03:12 marco-MS-5455 systemd[1]: lightdm.service: Failed with result 'exit-code'. Sep 12 20:03:13 marco-MS-5455 systemd[1]: lightdm.service: Scheduled restart job, restart counter is at 1. -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to lightdm in Ubuntu. https://bugs.launchpad.net/bugs/1943285 Title: login screen lagging. Status in lightdm package in Ubuntu: New Bug description: After boot or logout, login screen slow to appear, and I cannot type in my password for 4 to 5 seconds after login screen has appeared. ProblemType: Bug DistroRelease: Ubuntu 20.04 Package: lightdm 1.30.0-0ubuntu4~20.04.1 ProcVersionSignature: Ubuntu 5.4.0-84.94-generic 5.4.133 Uname: Linux 5.4.0-84-generic x86_64 ApportVersion: 2.20.11-0ubuntu27.18 Architecture: amd64 CasperMD5CheckResult: skip CurrentDesktop: MATE Date: Fri Sep 10 21:37:00 2021 InstallationDate: Installed on 2020-05-05 (493 days ago) InstallationMedia: Ubuntu-MATE 20.04 LTS "Focal Fossa" - Release amd64 (20200423) LightdmConfig: [Seat:*] autologin-guest=false greeter-show-manual-login=false greeter-session=slick-greeter SourcePackage: lightdm UpgradeStatus: No upgrade log present (probably fresh install) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/lightdm/+bug/1943285/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp