Failed to Start LightDM after Rebase to Custom Container Image

General
1

Hi, I’m working on making a custom UBlue spin with XFCE. When I run the rpm-ostree rebase command and reboot, Lightdm refuses to start.

Here are the failing services (lightdm and it’s user service):

× lightdm.service - Light Display Manager
     Loaded: loaded (/usr/lib/systemd/system/lightdm.service; enabled; preset: enabled)
    Drop-In: /usr/lib/systemd/system/service.d
             └─10-timeout-abort.conf
     Active: failed (Result: exit-code) since Wed 2025-08-20 15:39:35 EDT; 1min 9s ago
   Duration: 1.586s
 Invocation: 0df0374b817a4bd893902fbbe4e2bfb0
       Docs: man:lightdm(1)
    Process: 1937 ExecStart=/usr/sbin/lightdm (code=exited, status=1/FAILURE)
   Main PID: 1937 (code=exited, status=1/FAILURE)

Aug 20 15:39:35 elliot-gaz systemd[1]: lightdm.service: Scheduled restart job, restart counter is at 5.
Aug 20 15:39:35 elliot-gaz systemd[1]: lightdm.service: Start request repeated too quickly.
Aug 20 15:39:35 elliot-gaz systemd[1]: lightdm.service: Failed with result 'exit-code'.
Aug 20 15:39:35 elliot-gaz systemd[1]: Failed to start lightdm.service - Light Display Manager.
Aug 20 15:39:35 elliot-gaz systemd[1]: lightdm.service: Triggering OnFailure= dependencies.

× user@964.service - User Manager for UID 964
     Loaded: loaded (/usr/lib/systemd/system/user@.service; static)
    Drop-In: /usr/lib/systemd/system/user@.service.d
             └─00-uresourced.conf, 10-login-barrier.conf
             /usr/lib/systemd/system/service.d
             └─10-timeout-abort.conf
             /etc/systemd/system.control/user@964.service.d
             └─50-CPUWeight.conf, 50-IOWeight.conf, 50-MemoryLow.conf, 50-MemoryMin.conf
     Active: failed (Result: exit-code) since Wed 2025-08-20 15:39:35 EDT; 1min 9s ago
 Invocation: 51630649f7854e788dba12118813391f
       Docs: man:user@.service(5)
    Process: 1960 ExecStart=/usr/lib/systemd/systemd --user (code=exited, status=224/PAM)
   Main PID: 1960 (code=exited, status=224/PAM)
   Mem peak: 2.3M
        CPU: 9ms

Aug 20 15:39:35 elliot-gaz systemd[1]: Starting user@964.service - User Manager for UID 964...
Aug 20 15:39:35 elliot-gaz unix_chkpwd[1962]: could not obtain user info (lightdm)
Aug 20 15:39:35 elliot-gaz (systemd)[1960]: PAM failed: Authentication service cannot retrieve authentication info
Aug 20 15:39:35 elliot-gaz (systemd)[1960]: user@964.service: Failed to set up PAM session: Operation not permitted
Aug 20 15:39:35 elliot-gaz (systemd)[1960]: user@964.service: Failed at step PAM spawning /usr/lib/systemd/systemd: Operation not permitted
Aug 20 15:39:35 elliot-gaz systemd[1]: user@964.service: Main process exited, code=exited, status=224/PAM
Aug 20 15:39:35 elliot-gaz systemd[1]: user@964.service: Failed with result 'exit-code'.
Aug 20 15:39:35 elliot-gaz systemd[1]: Failed to start user@964.service - User Manager for UID 964.

And the project for the image can be found here.

What could be the issue?