I don't have an explanation of the behavior of pam-auth-update, but Debian bug #923362 has also just been filed regarding pam_systemd inexplicably getting disabled, and may be related.
** Bug watch added: Debian Bug tracker #923362 https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=923362 ** Also affects: pam (Debian) via https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=923362 Importance: Unknown Status: Unknown -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to pam in Ubuntu. https://bugs.launchpad.net/bugs/1817897 Title: attempting to enable fingerprint with pam-auth-update breaks gdm Status in pam package in Ubuntu: New Status in pam package in Debian: Unknown Bug description: I ran sudo pam-auth-update, enabled "Fingerprint authentication", selected "OK", and then rebooted. GDM wouldn't start after the reboot: Feb 27 06:29:41 jik-x1 /usr/lib/gdm3/gdm-wayland-session[1551]: dbus-daemon[1553]: [session uid=121 pid=1553] Activating service name='org.freedesktop.systemd1' requested by ':1.0' (uid=121 pid=1551 comm="/usr/lib/gdm3/gdm-wayland-session gnome-session --" label="unconfined") Feb 27 06:29:41 jik-x1 /usr/lib/gdm3/gdm-wayland-session[1551]: dbus-daemon[1553]: [session uid=121 pid=1553] Activated service 'org.freedesktop.systemd1' failed: Process org.freedesktop.systemd1 exited with status 1 Feb 27 06:29:41 jik-x1 /usr/lib/gdm3/gdm-wayland-session[1551]: Unable to register display with display manager I logged in on a VT and ran pam-auth-update again. I observed that "Register user sessions in the systemd control group" was not selected, even though my recollection was that it had been selected before I enabled fingerprint authentication, and I didn't disable it. I unselected fingerprint authentication and selected "Register user sessions in the systemd control group" and rebooted again. GDM started working again. ProblemType: Bug DistroRelease: Ubuntu 19.04 Package: libpam-runtime 1.3.1-5ubuntu1 ProcVersionSignature: Ubuntu 4.19.0-13.14-generic 4.19.20 Uname: Linux 4.19.0-13-generic x86_64 ApportVersion: 2.20.10-0ubuntu21 Architecture: amd64 CurrentDesktop: ubuntu:GNOME Date: Wed Feb 27 06:31:32 2019 InstallationDate: Installed on 2019-02-26 (0 days ago) InstallationMedia: Ubuntu 18.04.2 LTS "Bionic Beaver" - Release amd64 (20190210) PackageArchitecture: all SourcePackage: pam UpgradeStatus: Upgraded to disco on 2019-02-26 (0 days ago) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/pam/+bug/1817897/+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
