LightDM gets stuck in a loop after upgrading to Ubuntu MATE 24.10

Support & Help Requests
, ,
41

These are the two services that might conflict; and their status on my machine:

user@home~$: systemctl status [email protected] plymouth-quit.service
○ [email protected] - Getty on tty7
     Loaded: loaded (/usr/lib/systemd/system/[email protected]; disabled; preset: enabled)
     Active: inactive (dead)
       Docs: man:agetty(8)
             man:systemd-getty-generator(8)
             https://0pointer.de/blog/projects/serial-console.html

○ plymouth-quit.service - Terminate Plymouth Boot Screen
     Loaded: loaded (/usr/lib/systemd/system/plymouth-quit.service; static)
     Active: inactive (dead)

Also check cat /etc/X11/default-display-manager - it should be
/usr/sbin/lightdm.

1 Like
42

Looks like both are running at the same time for me.

jadams@jadams-Vivobook-Go-E1504FA-E1504FA:~$ sudo systemctl status [email protected] plymouth-quit.service
○ [email protected] - Getty on tty7
     Loaded: loaded (/usr/lib/systemd/system/[email protected]; disabled; preset: enabled)
     Active: inactive (dead)
       Docs: man:agetty(8)
             man:systemd-getty-generator(8)
             https://0pointer.de/blog/projects/serial-console.html

● plymouth-quit.service - Terminate Plymouth Boot Screen
     Loaded: loaded (/usr/lib/systemd/system/plymouth-quit.service; static)
     Active: active (exited) since Sat 2025-01-18 20:11:11 EST; 16min ago
 Invocation: cf2a211ad3334c799c7a28f290357223
    Process: 1339 ExecStart=/usr/bin/plymouth quit (code=exited, status=0/SUCCESS)
   Main PID: 1339 (code=exited, status=0/SUCCESS)
   Mem peak: 1.5M
        CPU: 11ms

Jan 18 20:11:11 jadams-Vivobook-Go-E1504FA-E1504FA systemd[1]: Starting plymouth-quit.service - Terminate Plymouth Boot Screen...
Jan 18 20:11:11 jadams-Vivobook-Go-E1504FA-E1504FA systemd[1]: Finished plymouth-quit.service - Terminate Plymouth Boot Screen.

I disabled plymouth-quit.service and will see how it goes.

Looks like lightdm is set as my display manager.

jadams@jadams-Vivobook-Go-E1504FA-E1504FA:~$ cat /etc/X11/default-display-manager 
/usr/sbin/lightdm
43

I wouldn't disable plymouth quit service.

1 Like
44

Try using the nosplash option on your next boot. Bring up the GRUB menu, press e to edit the boot command, and remove splash and add nosplash to the line that starts with

linux   /boot/vmlinuz- ... root=UUID=... ro  quiet splash

Then press F10 (I think - check the info at the bottom of the screen) to run with nosplash.

2 Likes
45

Sounds good, I'll re-enable the Plymouth quit service and try the "no splash" option when I boot next.

I'll let you know how it goes.

Thanks for your help, Stephen.

1 Like
46

FYI:

I installed um2410 on a VM, did not experience the loops you described.

image
image1280×874 277 KB

1 Like
47

Hi Pavlos,

That is good. This means that the situation is unique to my upgrade experience and likely something got corrupted during the process (i.e., LightDM installing the Unity greeter and not the Slick greeter).

I have also installed Ubuntu MATE 24.10 in a VM on this machine and I had no issues. I wanted to see how the upgrade process was to go from UM 24.04 to UM 24.10 for my own curiosity, but unfortunately encountered the issues I mentioned in this thread.

Though it was frustrating, I am grateful for the help of the community and I also gained knowledge on how to troubleshoot LightDM issues and what to look for, since I have never had to do this kind of troubleshooting before. All knowledge gained is valuable and, now that I have gone through this, if these issues come up in the future, I know what to do on my own next time (which in my opinion is a good way to look at life in general, not just Linux).

Many thanks,

Jaymo

1 Like
48

As far as I understood from the article, running

sudo dpkg-reconfigure lightdm

is enough to re-enable lightdm.service on Debian-based systems.

4 Likes
49

Thanks to this forum, I have never even attempted an upgrade process :sweat_smile: It seems to be a common source of trouble. Which is a shame!

You might also want to experiment with the upgrade within a VM (i.e. install 24.04 and then upgrade within)? I find it very odd that the upgrade installed Unity greeter apropos of nothing. Package dependencies are a weird, tangled nightmare.

3 Likes
50

I think that the 24.04 -> 24.10 upgrade process has problems. Similar situation is described in this thread:

1 Like
51

I haven't solved the issue either. 24.10 has installed Kernel 6.11.0.13
If, from the boot options, I chose 6.11.0.9 it all works like normal
I don't fill like playing around anymore. I'll wait for the next upgrade and see what happens.

W

52

I will give this a shot as well next time I boot up my laptop. Thanks.

Good to know. I also saw that Watford had troubles reading the responses to this thread.

If I can't get LightDM to work properly I'll just install UM 24.10 from scratch on the laptop and try the upgrade in a VM. It is unfortunate that the upgrade process seems to give several people major troubles despite the reason.

2 Likes
53

This ended up working for me and enabled LightDM.

Took a bit of dealing with a broken MATE DE, disabling then enabling dbus from a couple Ubuntu forum posts, and finally FINALLY all seems to be working right.

4 Likes
54

That's good news, thank you for reporting back!

1 Like
55

So we can say that the splash screen was not an issue, right?

1 Like
56

@stephematician correct. I disabled the splash screen as you instructed but it did not change that I was booting into TTY at that point. Re-enabling/disabling the splash screen did not change this.

The only fix was sudo dpkg-reconfigure lightdm and this was the only way I could re-enable LightDM.

Thanks

Jaymo

5 Likes
57

Thanks. I think I understand now that - prior to fixing up lightdm - the plymouth-quit.service had executed (and succeeded) but this didn't trigger lightdm and fully stop the splash screen exit service - but the fault was lightdm all along.

3 Likes
58

Exactly. Something wrong with lightdm or how I was trying to re-enable it was incorrect.

1 Like
59

I have some insight:

$ sudo systemctl disable lightdm

Synchronizing state of lightdm.service with SysV service script with /usr/lib/systemd/systemd-sysv-install.
Executing: /usr/lib/systemd/systemd-sysv-install disable lightdm
Removed "/etc/systemd/system/display-manager.service".

At least some important symlink gets removed and has to be restored:

$ ls -l  /etc/systemd/system/display-manager.service
lrwxrwxrwx 1 root root 35 Jan 22 19:00 /etc/systemd/system/display-manager.service -> /lib/systemd/system/lightdm.service
4 Likes