lightdm fails to start: X.Org X server: (EE) no screens found

[pmenzel]

After logging out on theinternet, lightdm did not come back:

@theinternet:~$ systemctl status lightdm
● lightdm.service - LightDM
   Loaded: loaded (/etc/systemd/system/lightdm.service; enabled; vendor preset: enabled)
   Active: failed (Result: exit-code) since Wed 2022-12-07 15:36:38 CET; 4min 43s ago
  Process: 19819 ExecStart=/usr/bin/lightdm (code=exited, status=1/FAILURE)
 Main PID: 19819 (code=exited, status=1/FAILURE)
      CPU: 486ms
@theinternet:~$ sudo journalctl -b
[…]
Dec 07 15:30:31 theinternet.molgen.mpg.de systemd[1]: forensicsd.service: Consumed 75ms CPU time.
Dec 07 15:36:33 theinternet.molgen.mpg.de systemd-logind[380]: Session c22 logged out. Waiting for processes to exit.
Dec 07 15:36:33 theinternet.molgen.mpg.de unknown[5248]: Name org.xfce.Xfconf lost on the message dbus, exiting.
Dec 07 15:36:33 theinternet.molgen.mpg.de org.gtk.vfs.Daemon[5233]: A connection to the bus can't be made
Dec 07 15:36:33 theinternet.molgen.mpg.de org.a11y.Bus[5233]: X connection to :0 broken (explicit kill or server shutdown).
Dec 07 15:36:33 theinternet.molgen.mpg.de org.gtk.vfs.Daemon[5233]: A connection to the bus can't be made
Dec 07 15:36:33 theinternet.molgen.mpg.de org.gtk.vfs.Daemon[5233]: A connection to the bus can't be made
Dec 07 15:36:34 theinternet.molgen.mpg.de systemd[1]: lightdm.service: Main process exited, code=exited, status=1/FAILURE
Dec 07 15:36:34 theinternet.molgen.mpg.de systemd[1]: lightdm.service: Failed with result 'exit-code'.
Dec 07 15:36:34 theinternet.molgen.mpg.de systemd[1]: lightdm.service: Consumed 1h 19min 5.991s CPU time.
Dec 07 15:36:34 theinternet.molgen.mpg.de systemd[1]: lightdm.service: Service RestartSec=100ms expired, scheduling restart.
Dec 07 15:36:34 theinternet.molgen.mpg.de systemd[1]: lightdm.service: Scheduled restart job, restart counter is at 1.
Dec 07 15:36:34 theinternet.molgen.mpg.de systemd[1]: Stopped LightDM.
Dec 07 15:36:34 theinternet.molgen.mpg.de systemd[1]: lightdm.service: Consumed 1h 19min 5.991s CPU time.
Dec 07 15:36:34 theinternet.molgen.mpg.de systemd[1]: Starting LightDM...
Dec 07 15:36:34 theinternet.molgen.mpg.de systemd[1]: Started LightDM.
Dec 07 15:36:34 theinternet.molgen.mpg.de lightdm[19792]: Error getting user list from org.freedesktop.Accounts: GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The name org.freedesktop.Accounts was not provided by any .service files
Dec 07 15:36:35 theinternet.molgen.mpg.de systemd[1]: lightdm.service: Main process exited, code=exited, status=1/FAILURE
Dec 07 15:36:35 theinternet.molgen.mpg.de systemd[1]: lightdm.service: Failed with result 'exit-code'.
Dec 07 15:36:35 theinternet.molgen.mpg.de systemd[1]: lightdm.service: Consumed 493ms CPU time.
Dec 07 15:36:35 theinternet.molgen.mpg.de systemd[1]: lightdm.service: Service RestartSec=100ms expired, scheduling restart.
Dec 07 15:36:35 theinternet.molgen.mpg.de systemd[1]: lightdm.service: Scheduled restart job, restart counter is at 2.
Dec 07 15:36:35 theinternet.molgen.mpg.de systemd[1]: Stopped LightDM.
Dec 07 15:36:35 theinternet.molgen.mpg.de systemd[1]: lightdm.service: Consumed 493ms CPU time.
[…]

@theinternet:~$ sudo cat /var/log/lightdm/x-0.log
X.Org X Server 1.21.1.4
X Protocol Version 11, Revision 0
Current Operating System: Linux theinternet.molgen.mpg.de 5.15.77.mx64.440 #1 SMP Tue Nov 8 15:42:33 CET 2022 x86_64
Kernel command line: BOOT_IMAGE=/boot/bzImage-5.15.77.mx64.440 root=LABEL=root ro crashkernel=64G-:256M console=ttyS0,115200n8 console=tty0 init=/bin/systemd audit=0 random.trust_cpu=on systemd.unified_cgroup_hierarchy
 
Current version of pixman: 0.38.4
        Before reporting problems, check http://wiki.x.org
        to make sure that you have the latest version.
Markers: (--) probed, (**) from config file, (==) default setting,
        (++) from command line, (!!) notice, (II) informational,
        (WW) warning, (EE) error, (NI) not implemented, (??) unknown.
(==) Log file: "/var/log/Xorg.0.log", Time: Wed Dec  7 15:36:37 2022
(==) Using config directory: "/etc/X11/xorg.conf.d"
(==) Using system config directory "/usr/share/X11/xorg.conf.d"
(EE) nouveau: module ABI major version (24) doesn't match the server's version (25)
(EE) 
Fatal server error:
(EE) no screens found(EE) 
(EE) 
Please consult the The X.Org Foundation support 
         at http://wiki.x.org
 for help. 
(EE) Please also check the log file at "/var/log/Xorg.0.log" for additional information.
(EE) 
(EE) Server terminated with error (1). Closing log file.

[pmenzel]

The nouveau error seems to have been a red herring. Removing and inserting the proprietary Nvidia modules fixed it somehow.

@theinternet:~/bee-files (master)$ sudo rmmod nvidia_drm
@theinternet:~/bee-files (master)$ sudo rmmod nvidia
rmmod: ERROR: Module nvidia is in use by: nvidia_uvm nvidia_modeset
@theinternet:~/bee-files (master)$ sudo rmmod nvidia_modeset
@theinternet:~/bee-files (master)$ sudo rmmod nvidia_uvm
@theinternet:~/bee-files (master)$ sudo rmmod nvidia
@theinternet:~/bee-files (master)$ sudo modprobe nvidia
modprobe: FATAL: Module nvidia not found in directory /lib/modules/5.15.77.mx64.440
@theinternet:~/bee-files (master)$ sudo insmod nvidia
insmod: ERROR: could not load module nvidia: No such file or directory
@theinternet:~/bee-files (master)$ sudo /sbin/nvidiactl
mknod: /dev/nvidia0: File exists
mknod: /dev/nvidia1: File exists
mknod: /dev/nvidiactl: File exists
mknod: /dev/nvidia-uvm: File exists

@theinternet:~/bee-files (master)$ systemctl status lightdm
● lightdm.service - LightDM
   Loaded: loaded (/etc/systemd/system/lightdm.service; enabled; vendor preset: enabled)
   Active: active (running) since Wed 2022-12-07 15:50:08 CET; 11s ago
 Main PID: 20591 (lightdm)
    Tasks: 7 (limit: 4915)
   Memory: 32.9M
      CPU: 2.300s
   CGroup: /system.slice/lightdm.service
           ├─20591 /usr/bin/lightdm
           ├─20596 /usr/libexec/Xorg :0 -seat seat0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch
           └─20665 lightdm --session-child 14 21