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

jaymo_chicago · 18 January 2025 15:35

Hello all,

I upgraded my laptop to Ubuntu MATE 24.10. The upgrade process went smoothly, but as soon as I rebooted my laptop, LightDM seems to get stuck in some sort of loop. The screen goes black after the UM splash screen, I see the cursor for about half a second otherwise just a blank screen, then after about 5 seconds it tries again to load LightDM with the same visual results.

I tried reinstalling LightDM twice to no avail by following this procedure:

Pressing Shift on boot until I get the GRUB menu and I boot into Recovery mode under the most updated kernel.
Using the recovery options to open a CLI interface under root.
Run apt purge lightdm, then apt install lightdm to reinstall LightDM (the second time I tried updating the system before running this and removing dependencies, but no changes).
Reboot the machine.

The laptop running this is an Asus Vivobook, AMD Ryzen 7000 series graphics. Upgrade path was UM 24.04 LTS to UM 24.10.

Not sure how I can share any information directly from the system since I can't even boot into it at the moment.

Any help would be greatly appreciated.

Many thanks,

Jaymo

pavlos_kairis · 18 January 2025 16:11

using another pc, you should be able to ssh to the laptop and see what's going on. Go to /var/log/ and look for syslog issues or even in the lightdm/ dir.

Since you can boot in text mode, inxi -F would help.

jaymo_chicago · 18 January 2025 17:42

Hi Pavlos,

Thanks for your help. I was unable to ssh from my production machine to this laptop, but in the recovery console I was able to disable lightdm, log in through TTY and start UM with startx. I went through syslog and found this line repeated several times (did cat syslog | grep lightdm):

2025-01-18T10:13:33.174426-05:00 jadams-Vivobook-Go-E1504FA-E1504FA lightdm[1406]: Seat type 'xlocal' is deprecated, use 'type=local' instead

The file seat0-greeter.log under /var/log/lightdm seems to have some information too.

[+0.00s] DEBUG: unity-greeter.vala:562: Starting unity-greeter 17.04.1 UID=110 LANG=en_US.UTF-8
[+0.00s] DEBUG: unity-greeter.vala:565: Setting cursor
[+0.00s] DEBUG: unity-greeter.vala:579: Loading command line options
[+0.00s] DEBUG: unity-greeter.vala:607: Setting GTK+ settings
[+0.01s] DEBUG: Using cross-namespace EXTERNAL authentication (this will deadlock if server is GDBus < 2.73.3)
[+0.04s] DEBUG: _g_io_module_get_default: Found default implementation gvfs (GDaemonVfs) for ‘gio-vfs’
[+0.07s] DEBUG: _g_io_module_get_default: Found default implementation dconf (DConfSettingsBackend) for ‘gsettings-backend’
[+0.09s] DEBUG: unity-greeter.vala:630: Creating Unity Greeter
[+0.09s] DEBUG: Connecting to display manager...
[+0.09s] DEBUG: Wrote 26 bytes to daemon
[+0.09s] DEBUG: Read 8 bytes from daemon
[+0.09s] DEBUG: Read 157 bytes from daemon
[+0.09s] DEBUG: Connected api=1 version=1.30.0 hide-users=false has-guest-account=false default-session=mate show-manual-login=false show-remote-login=true
[+0.10s] DEBUG: Using cross-namespace EXTERNAL authentication (this will deadlock if server is GDBus < 2.73.3)
[+0.11s] DEBUG: setenv()/putenv() are not thread-safe and should not be used after threads are created
[+0.12s] DEBUG: unity-greeter.vala:680: Starting main loop
[+0.12s] DEBUG: settings-daemon.vala:75: Acquired org.gnome.SessionManager
[+0.12s] DEBUG: settings-daemon.vala:102: Acquired org.gnome.ScreenSaver
[+0.12s] DEBUG: settings-daemon.vala:159: All bus names acquired, starting unity-settings-daemon
Failed to start indicator-session.service: Unit indicator-session.service not found.
[+0.37s] DEBUG: unity-greeter.vala:123: xsettings is ready
[+0.37s] DEBUG: unity-greeter.vala:497: Creating background surface

** (unity-settings-daemon:1771): WARNING **: 10:24:02.275: Unable to register client: GDBus.Error:org.freedesktop.DBus.Error.UnknownMethod: No such method “RegisterClient”
[+0.37s] DEBUG: setenv()/putenv() are not thread-safe and should not be used after threads are created
[+0.38s] DEBUG: setenv()/putenv() are not thread-safe and should not be used after threads are created
[+0.38s] DEBUG: setenv()/putenv() are not thread-safe and should not be used after threads are created
[+0.38s] DEBUG: setenv()/putenv() are not thread-safe and should not be used after threads are created
[+0.38s] DEBUG: setenv()/putenv() are not thread-safe and should not be used after threads are created
[+0.38s] DEBUG: menubar.vala:335: LANG=en_US.UTF-8 LANGUAGE=(null)
[+0.39s] WARNING: File '/usr/lib/indicators3/7/libcom.canonical.indicator.session.so' does not exist.
[+0.39s] WARNING: File '/usr/lib/indicators3/7/com.canonical.indicator.session.so' does not exist.
[+0.39s] WARNING: File '/usr/lib/indicators3/7/com.canonical.indicator.session' does not exist.
[+0.39s] DEBUG: menubar.vala:367: LANG=en_US.UTF-8 LANGUAGE=(null)
[+0.40s] DEBUG: Using cross-namespace EXTERNAL authentication (this will deadlock if server is GDBus < 2.73.3)
[+0.40s] DEBUG: Loading users from org.freedesktop.Accounts
[+0.40s] DEBUG: User /org/freedesktop/Accounts/User1000 added
[+0.43s] DEBUG: user-list.vala:1030: Adding/updating user jadams (Jaymeson Adams)
[+0.43s] DEBUG: Loading sessions from org.freedesktop.DisplayManager
[+0.43s] DEBUG: Loaded session /usr/share/xsessions/mate.desktop (MATE, This session logs you into MATE)
[+0.43s] DEBUG: Starting authentication for user jadams...
[+0.43s] DEBUG: Wrote 22 bytes to daemon
[+0.45s] DEBUG: main-window.vala:187: Screen is 1920x1080 pixels
[+0.45s] DEBUG: main-window.vala:195: Monitor 0 is 1920x1080 pixels at 0,0
[+0.45s] DEBUG: unity-greeter.vala:636: Showing greeter
[+0.45s] DEBUG: unity-greeter.vala:257: Showing main window
[+0.45s] DEBUG: Read 8 bytes from daemon
[+0.45s] DEBUG: Read 36 bytes from daemon
[+0.45s] DEBUG: Prompt user with 1 message(s)
[+0.46s] DEBUG: user-list.vala:1030: Adding/updating user jadams (Jaymeson Adams)
[+0.46s] DEBUG: Connected to Application Indicator Service.
Segmentation fault (core dumped)
[+0.00s] DEBUG: unity-greeter.vala:562: Starting unity-greeter 17.04.1 UID=110 LANG=en_US.UTF-8
[+0.00s] DEBUG: unity-greeter.vala:565: Setting cursor
[+0.00s] DEBUG: unity-greeter.vala:579: Loading command line options
[+0.00s] DEBUG: unity-greeter.vala:607: Setting GTK+ settings
[+0.00s] DEBUG: Using cross-namespace EXTERNAL authentication (this will deadlock if server is GDBus < 2.73.3)
[+0.01s] DEBUG: _g_io_module_get_default: Found default implementation gvfs (GDaemonVfs) for ‘gio-vfs’
[+0.05s] DEBUG: _g_io_module_get_default: Found default implementation dconf (DConfSettingsBackend) for ‘gsettings-backend’
[+0.08s] DEBUG: unity-greeter.vala:630: Creating Unity Greeter
[+0.08s] DEBUG: Connecting to display manager...
[+0.08s] DEBUG: Wrote 26 bytes to daemon
[+0.08s] DEBUG: Read 8 bytes from daemon
[+0.08s] DEBUG: Read 157 bytes from daemon
[+0.08s] DEBUG: Connected api=1 version=1.30.0 hide-users=false has-guest-account=false default-session=mate show-manual-login=false show-remote-login=true
[+0.08s] DEBUG: Using cross-namespace EXTERNAL authentication (this will deadlock if server is GDBus < 2.73.3)
[+0.10s] DEBUG: setenv()/putenv() are not thread-safe and should not be used after threads are created
[+0.11s] DEBUG: unity-greeter.vala:680: Starting main loop
[+0.11s] DEBUG: settings-daemon.vala:75: Acquired org.gnome.SessionManager
[+0.11s] DEBUG: settings-daemon.vala:102: Acquired org.gnome.ScreenSaver
[+0.11s] DEBUG: settings-daemon.vala:159: All bus names acquired, starting unity-settings-daemon
Failed to start indicator-session.service: Unit indicator-session.service not found.
[+0.20s] DEBUG: unity-greeter.vala:123: xsettings is ready
[+0.20s] DEBUG: unity-greeter.vala:497: Creating background surface

** (unity-settings-daemon:2042): WARNING **: 10:24:10.384: Unable to register client: GDBus.Error:org.freedesktop.DBus.Error.UnknownMethod: No such method “RegisterClient”
[+0.20s] DEBUG: setenv()/putenv() are not thread-safe and should not be used after threads are created
[+0.20s] DEBUG: setenv()/putenv() are not thread-safe and should not be used after threads are created
[+0.21s] DEBUG: setenv()/putenv() are not thread-safe and should not be used after threads are created
[+0.21s] DEBUG: setenv()/putenv() are not thread-safe and should not be used after threads are created
[+0.21s] DEBUG: setenv()/putenv() are not thread-safe and should not be used after threads are created
[+0.21s] DEBUG: menubar.vala:335: LANG=en_US.UTF-8 LANGUAGE=(null)
[+0.21s] WARNING: File '/usr/lib/indicators3/7/libcom.canonical.indicator.session.so' does not exist.
[+0.21s] WARNING: File '/usr/lib/indicators3/7/com.canonical.indicator.session.so' does not exist.
[+0.21s] WARNING: File '/usr/lib/indicators3/7/com.canonical.indicator.session' does not exist.
[+0.22s] DEBUG: menubar.vala:367: LANG=en_US.UTF-8 LANGUAGE=(null)
[+0.22s] DEBUG: Using cross-namespace EXTERNAL authentication (this will deadlock if server is GDBus < 2.73.3)
[+0.22s] DEBUG: Loading users from org.freedesktop.Accounts
[+0.22s] DEBUG: User /org/freedesktop/Accounts/User1000 added
[+0.24s] DEBUG: user-list.vala:1030: Adding/updating user jadams (Jaymeson Adams)
[+0.24s] DEBUG: Loading sessions from org.freedesktop.DisplayManager
[+0.25s] DEBUG: Loaded session /usr/share/xsessions/mate.desktop (MATE, This session logs you into MATE)
[+0.25s] DEBUG: Starting authentication for user jadams...
[+0.25s] DEBUG: Wrote 22 bytes to daemon
[+0.27s] DEBUG: main-window.vala:187: Screen is 1920x1080 pixels
[+0.27s] DEBUG: main-window.vala:195: Monitor 0 is 1920x1080 pixels at 0,0
[+0.27s] DEBUG: unity-greeter.vala:636: Showing greeter
[+0.27s] DEBUG: unity-greeter.vala:257: Showing main window
[+0.27s] DEBUG: Read 8 bytes from daemon
[+0.27s] DEBUG: Read 36 bytes from daemon
[+0.27s] DEBUG: Prompt user with 1 message(s)
Segmentation fault (core dumped)

Hopefully this helps for troubleshooting. I've never had to debug my system like this before (though it's a great learning experience) -- my production machine runs Ubuntu MATE 24.04 LTS with no problems at all, and this machine I just wanted to see how the upgrade would go and what's happening in 24.10 (i.e., my "hobby" machine).

Thanks,

Jaymo

pavlos_kairis · 18 January 2025 18:02

I dont have a 24.10 to test but in 24.04 cat /etc/lightdm/lightdm.conf

my username is user

[Seat:*]
autologin-guest=false
autologin-user=user
autologin-user-timeout=0

maybe someone who has 24.10 can help out.

(install openssh-server on the laptop, then you should be able to ssh to it)

xlocal appears in /usr/share/lightdm/lighdm.conf.d/90-nvidia.conf

Install arctica-greeter with sudo apt install arctica-greeter

this may work.

ironfoot · 18 January 2025 20:24

Check this first (the .Xauthority part):

https://wiki.archlinux.org/title/LightDM#Infinite_login_loop

From Ubuntu MATE 24.10 release notes:

Switched back to Slick Greeter (replacing Arctica Greeter) due to race-condition in the boot process which results the display manager failing to initialise.

Was slick-greeter installed and arctica-greeter removed during the upgrade process?

jaymo_chicago · 18 January 2025 21:22

Hi Pavlos and Ironfoot,

Many thanks for the help. I tried both the suggestions (the Xauthority solution from the ArchWiki and installing Arctica Greeter) and unfortunately the problem still persists.

I noticed some things though as I was going through the troubleshooting:

There is no lightdm.conf file in /etc/lightdm as it shows in the ArchWiki.
When I installed the Arctica Greeter with sudo apt install arctica-greeter, there were many Ayatana indicators that needed to be installed and a "unity-control-center" package to be removed. Strange as I am not using Unity.
I do not have a 90-nvidia.conf file under /etc/lightdm.conf.d.

I appreciate the help. However, it's starting to seem that the update went pretty badly, if there's missing packages and LightDM is not working.

Thanks,

Jaymo

ironfoot · 18 January 2025 21:37

What is the output from lightdm --show-config?

jaymo_chicago · 18 January 2025 22:11

jadams@jadams-Vivobook-Go-E1504FA-E1504FA:~$ lightdm --show-config
   [Seat:*]
J  greeter-session=arctica-greeter
D  greeter-wrapper=/usr/lib/lightdm/lightdm-greeter-session
K  allow-guest=true
E  guest-wrapper=/usr/lib/lightdm/lightdm-guest-session
F  user-session=mate
H  xserver-command=X -core
I  type=xlocal
I  display-setup-script=/sbin/prime-offload
I  display-stopped-script=/sbin/prime-switch
L  greeter-show-manual-login=false
J  greeter-show-remote-login=true
K  greeter-allow-guest=true

   [LightDM]
C  backup-logs=false
K  guest-account-script=arctica-greeter-guest-account-script

Sources:
A  /usr/share/lightdm/lightdm.conf.d/50-arctica-greeter.conf
B  /usr/share/lightdm/lightdm.conf.d/50-disable-guest.conf
C  /usr/share/lightdm/lightdm.conf.d/50-disable-log-backup.conf
D  /usr/share/lightdm/lightdm.conf.d/50-greeter-wrapper.conf
E  /usr/share/lightdm/lightdm.conf.d/50-guest-wrapper.conf
F  /usr/share/lightdm/lightdm.conf.d/50-ubuntu-mate.conf
G  /usr/share/lightdm/lightdm.conf.d/50-unity-greeter.conf
H  /usr/share/lightdm/lightdm.conf.d/50-xserver-command.conf
I  /usr/share/lightdm/lightdm.conf.d/90-nvidia.conf
J  /etc/lightdm/lightdm.conf.d/90-arctica-greeter.conf
K  /etc/lightdm/lightdm.conf.d/91-arctica-greeter-guest-session.conf
L  /etc/lightdm/lightdm.conf.d/91-arctica-greeter-mate.conf

jaymo_chicago · 18 January 2025 22:15

Arctica Greeter was not installed. I didn't notice whether Slick Greeter was installed in its place but I checked if it is now, and it appears not.

jadams@jadams-Vivobook-Go-E1504FA-E1504FA:~$ apt list -i | grep slick

WARNING: apt does not have a stable CLI interface. Use with caution in scripts.

jadams@jadams-Vivobook-Go-E1504FA-E1504FA:~$

ironfoot · 18 January 2025 22:26

You had arctica-greeter in 24.04 by default. It had to be replaced with slick-greeter during the upgrade process (as release notes suggest), but something went wrong. After that, you have manually reinstalled arctica-greeter.

I suggest removing arctica-greeter again and reinstalling slick-greeter.

What does apt --simulate remove arctica-greeter say?

jaymo_chicago · 18 January 2025 22:27

jadams@jadams-Vivobook-Go-E1504FA-E1504FA:~$ apt --simulate remove arctica-greeter
NOTE: This is only a simulation!
      apt needs root privileges for real execution.
      Keep also in mind that locking is deactivated,
      so don't depend on the relevance to the real current situation!

The following packages were automatically installed and are no longer required:
  ayatana-indicator-a11y      espeak-ng     libgnomekbd8
  ayatana-indicator-keyboard  gkbd-capplet  numlockx
Use 'apt autoremove' to remove them.

REMOVING:
  arctica-greeter

Summary:
  Upgrading: 0, Installing: 0, Removing: 1, Not Upgrading: 1
Remv arctica-greeter [0.99.5.0-3ubuntu2]

ironfoot · 18 January 2025 22:30

Try:
sudo apt purge arctica-greeter
sudo apt install --reinstall slick-greeter

And then again:
lightdm --show-config

jaymo_chicago · 18 January 2025 22:33

I ran the commands, uninstalled arctica-greeter and installed slick-greeter.

I did not remove any packages that were suggested (i.e., automatically installed and no longer required.

Output of lightdm --show-config:

jadams@jadams-Vivobook-Go-E1504FA-E1504FA:~$ lightdm --show-config
   [Seat:*]
J  allow-guest=true
C  greeter-wrapper=/usr/lib/lightdm/lightdm-greeter-session
D  guest-wrapper=/usr/lib/lightdm/lightdm-guest-session
G  greeter-session=unity-greeter
F  user-session=mate
H  xserver-command=X -core
I  type=xlocal
I  display-setup-script=/sbin/prime-offload
I  display-stopped-script=/sbin/prime-switch
J  greeter-allow-guest=true
K  greeter-show-manual-login=false

   [LightDM]
B  backup-logs=false
J  guest-account-script=arctica-greeter-guest-account-script

Sources:
A  /usr/share/lightdm/lightdm.conf.d/50-disable-guest.conf
B  /usr/share/lightdm/lightdm.conf.d/50-disable-log-backup.conf
C  /usr/share/lightdm/lightdm.conf.d/50-greeter-wrapper.conf
D  /usr/share/lightdm/lightdm.conf.d/50-guest-wrapper.conf
E  /usr/share/lightdm/lightdm.conf.d/50-slick-greeter.conf
F  /usr/share/lightdm/lightdm.conf.d/50-ubuntu-mate.conf
G  /usr/share/lightdm/lightdm.conf.d/50-unity-greeter.conf
H  /usr/share/lightdm/lightdm.conf.d/50-xserver-command.conf
I  /usr/share/lightdm/lightdm.conf.d/90-nvidia.conf
J  /etc/lightdm/lightdm.conf.d/91-arctica-greeter-guest-session.conf
K  /etc/lightdm/lightdm.conf.d/91-arctica-greeter-mate.conf

ironfoot · 18 January 2025 22:37

This file is not supposed to be there. Where is it from?

dpkg -S /usr/share/lightdm/lightdm.conf.d/50-unity-greeter.conf

jaymo_chicago · 18 January 2025 22:40

I am not sure. I noticed something called unity-control-center that was removed when I installed arctica-greeter. I have no idea why there's Unity files in my installation. Originally did a clean install of UM 24.04 then upgraded to 24.10.

Output of dpkg -S /usr/share/lightdm/lightdm.conf.d/50-unity-greeter.conf:

jadams@jadams-Vivobook-Go-E1504FA-E1504FA:~$ dpkg -S  /usr/share/lightdm/lightdm.conf.d/50-unity-greeter.conf
unity-greeter: /usr/share/lightdm/lightdm.conf.d/50-unity-greeter.conf
jadams@jadams-Vivobook-Go-E1504FA-E1504FA:~$

ironfoot · 18 January 2025 22:43

You have unity-greeter package installed.

apt --simulate remove unity-greeter

jaymo_chicago · 18 January 2025 22:43

jadams@jadams-Vivobook-Go-E1504FA-E1504FA:~$ apt --simulate remove unity-greeter
NOTE: This is only a simulation!
      apt needs root privileges for real execution.
      Keep also in mind that locking is deactivated,
      so don't depend on the relevance to the real current situation!

The following packages were automatically installed and are no longer required:
  ayatana-indicator-a11y      espeak-ng     gsettings-ubuntu-schemas  libfcitx-config4   libfcitx-utils0  libunity-settings-daemon1  unity-settings-daemon
  ayatana-indicator-keyboard  gkbd-capplet  indicator-keyboard        libfcitx-gclient1  libido3-0.1-0    nautilus-data              unity-settings-daemon-schemas
Use 'apt autoremove' to remove them.

REMOVING:
  unity-greeter

Summary:
  Upgrading: 0, Installing: 0, Removing: 1, Not Upgrading: 1
Remv unity-greeter [24.10.1-0ubuntu1]

ironfoot · 18 January 2025 22:48

Well, it is not supposed to be there. Let's remove:

sudo apt remove --purge unity-greeter
sudo apt autoremove

jaymo_chicago · 18 January 2025 22:50

Done!

This is the new output of lightdm --show-config:

jadams@jadams-Vivobook-Go-E1504FA-E1504FA:~$ lightdm --show-config
   [Seat:*]
I  allow-guest=true
C  greeter-wrapper=/usr/lib/lightdm/lightdm-greeter-session
D  guest-wrapper=/usr/lib/lightdm/lightdm-guest-session
E  greeter-session=slick-greeter
F  user-session=mate
G  xserver-command=X -core
H  type=xlocal
H  display-setup-script=/sbin/prime-offload
H  display-stopped-script=/sbin/prime-switch
I  greeter-allow-guest=true
J  greeter-show-manual-login=false

   [LightDM]
B  backup-logs=false
I  guest-account-script=arctica-greeter-guest-account-script

Sources:
A  /usr/share/lightdm/lightdm.conf.d/50-disable-guest.conf
B  /usr/share/lightdm/lightdm.conf.d/50-disable-log-backup.conf
C  /usr/share/lightdm/lightdm.conf.d/50-greeter-wrapper.conf
D  /usr/share/lightdm/lightdm.conf.d/50-guest-wrapper.conf
E  /usr/share/lightdm/lightdm.conf.d/50-slick-greeter.conf
F  /usr/share/lightdm/lightdm.conf.d/50-ubuntu-mate.conf
G  /usr/share/lightdm/lightdm.conf.d/50-xserver-command.conf
H  /usr/share/lightdm/lightdm.conf.d/90-nvidia.conf
I  /etc/lightdm/lightdm.conf.d/91-arctica-greeter-guest-session.conf
J  /etc/lightdm/lightdm.conf.d/91-arctica-greeter-mate.conf

ironfoot · 18 January 2025 22:51

Yes, this looks much better.

apt list *indicator-*