[SOLVED] Light Display Manager failed to start at boot

chemicalMoss · 2021-07-01 14:06:31

Hello everbody,

I have troubles installing lightdm. I did a clean install of arch closely following the official installation guide. However, it appears that I am running into what appears to be permission related issue.

When I boot nearly always get a message [FAILED] Failed to start Light Display Manager. I instead login via tty. Checking systemctl status lightdm outputs this:

× lightdm.service - Light Display Manager
Loaded: loaded (/usr/lib/systemd/system/lightdm.service; enabled; vendor preset: disabled)
Active: failed (Result: exit-code) since Thu 2021-07-01 13:27:20 UTC; 3min 33s ago
Docs: man:lightdm(1)
Process: 415 ExecStart=/usr/bin/lightdm (code=exited, status=1/FAILURE)
Main PID: 415 (code=exited, status=1/FAILURE)
CPU: 34ms

Jul 01 13:27:20 arch systemd[1]: lightdm.service: Failed with result 'exit-code'.
Jul 01 13:27:20 arch systemd[1]: lightdm.service: Scheduled restart job, restart counter is at 5.
Jul 01 13:27:20 arch systemd[1]: Stopped Light Display Manager.
Jul 01 13:27:20 arch systemd[1]: lightdm.service: Start request repeated too quickly.
Jul 01 13:27:20 arch systemd[1]: lightdm.service: Failed with result 'exit-code'.
Jul 01 13:27:20 arch systemd[1]: Failed to start Light Display Manager.

When I run lightdm --test-mode --debug the output contains suspicious permission denied messages (Xauthority, ).
https://pastebin.com/gMySPWQr

Interestingly, I can get lightdm working by manually running systemctl start lightdm. However, on reboot it it extremely likely that I am back at the beginning. The laptop has a Ryzen CPU, with amdgpu video drivers, mesa, ... installed.

Here are the log files that I found to be relevant from other threads:
https://pastebin.com/38pqMqh9
https://pastebin.com/SLfq8qXf
https://pastebin.com/JgVdJ6Bx
https://pastebin.com/rAjAgaaG

Last edited by chemicalMoss (2021-07-02 11:26:02)

seth · 2021-07-01 14:12:45

https://wiki.archlinux.org/title/LightD … TTY_output
https://wiki.archlinux.org/title/Kernel … _KMS_start

chemicalMoss · 2021-07-01 14:23:50

Hey seth,

I made the assumption it wouldn't be a race condition, but I was wrong. The first link seems to have fix the issue. What part of the logs made you suspicious or was it based on instinct?
Thanks for the help!

Last edited by chemicalMoss (2021-07-01 14:24:47)

seth · 2021-07-01 14:26:33

When I boot nearly always get a message

Nondeterministic behavior is most likely a race condition and in this case most likely the linked one.
Using early KMS will get you a (slightly) faster system start and be more robust if you switch the DM (or use xinit)

Please always remember to mark resolved threads by editing your initial posts subject - so others will know that there's no task left, but maybe a solution to find.
Thanks.

bigo · 2021-07-02 02:01:13

Edit the display-manager.service config file.

change restart to always, restartsec to 0.5s.

vim /etc/systemd/system/display-manager.service

[Unit]                                                                                                                                     
  1 Description=Light Display Manager
  2 Documentation=man:lightdm(1)
  3 Conflicts=getty@tty1.service
  4 After=getty@tty1.service systemd-user-sessions.service plymouth-quit.service acpid.service
  5 
  6 [Service]
  7 ExecStart=/usr/bin/lightdm
  8 Restart=always
  9 RestartSec=0.5
 10 StartLimitInterval=0
 11 IgnoreSIGPIPE=no
 12 BusName=org.freedesktop.DisplayManager
 13 
 14 [Install]
 15 Alias=display-manager.service

Last edited by bigo (2021-07-02 08:28:29)

pdizzle · 2025-08-22 15:04:58

I realize this is really old but it ranks high on google searches. Do not do what that last post suggests, you will just be kicked into an infinite loop of attempting to restart lightDM and unable to use a TTY as you'll just keep getting kicked back to the TTY lightDM is attempting to start in. Trying to figure out how to undo this now

seth · 2025-08-22 15:07:34

2nd link below, boot the multi-user.target, fix the service from there
If you've an nvidia system and face a problem where the 580xx driver initializes too slow, the suggestion for now is to "ExecStartPre=usr/bin/sleep 1"

WorMzy · 2025-08-22 19:48:58

Mod note: closing this old topic.

Arch Linux

#1 2021-07-01 14:06:31

[SOLVED] Light Display Manager failed to start at boot

#2 2021-07-01 14:12:45

Re: [SOLVED] Light Display Manager failed to start at boot

#3 2021-07-01 14:23:50

Re: [SOLVED] Light Display Manager failed to start at boot

#4 2021-07-01 14:26:33

Re: [SOLVED] Light Display Manager failed to start at boot

#5 2021-07-02 02:01:13

Re: [SOLVED] Light Display Manager failed to start at boot

#6 2025-08-22 15:04:58

Re: [SOLVED] Light Display Manager failed to start at boot

#7 2025-08-22 15:07:34

Re: [SOLVED] Light Display Manager failed to start at boot

#8 2025-08-22 19:48:58

Re: [SOLVED] Light Display Manager failed to start at boot

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