SDDM issue? I can't log in with the correct password after AFKing

Big Scorpio · 2025-07-20 15:45:00

Hello Arch Friends,

I make this short.
After AFKing for long enough and my desktop environment (Cinnamon X11, not SW Render nor Wayland) locking out and i come back and I enter my CORRECT password multiple times, they all result in authentication failure.
I even entered my password in the username textbox to see if my password is being typed correctly and it is. So no caps lock or keyboard layout or anything similar is interfering with my password text being entered.

I can log in as root however but I can't use root for the things i want to use my computer for.

Tried restarting SDDM.
Tried using different desktop environment (XFCE) to see if it's not just a Cinnamon issue (?).
Tried switching between the tty terminals (CTRL + ALT + F<number>) but there's not even a video signal present, so i can't log in through the console.
Tried disabling SDDM and enabling LightDM but LightDM won't start for reasons unknown to me.

Nah, in the end it forces me to reboot my entire system /!\

Is SDDM broken or what? How to find the problem?

With kindest regards,

Update:

Here are some logs of LightDM:

[motherfucker_big_scorpio@Nexus ~]$ sudo systemctl restart lightdm
Job for lightdm.service failed because the control process exited with error code.
See "systemctl status lightdm.service" and "journalctl -xeu lightdm.service" for details.
[motherfucker_big_scorpio@Nexus ~]$ systemctl status lightdm.service
× lightdm.service - Light Display Manager
     Loaded: loaded (/usr/lib/systemd/system/lightdm
.service; disabled; preset: disabled)
     Active: failed (Result: exit-code) since Sun 2025-07-20 17:50:00 CEST; 9s ago
 Invocation: 2adead9fdf244d178a8b2267f6b8b03d
       Docs: man:lightdm(1)
    Process: 4061 ExecStart=/usr/bin/lightdm (code=exited, status=1/FAILURE)
   Main PID: 4061 (code=exited, status=1/FAILURE)

Jul 20 17:50:00 Nexus systemd[1]: lightdm.service: Scheduled restart job, restart counter is at 5.
Jul 20 17:50:00 Nexus systemd[1]: lightdm.service: Start request repeate
d too quickly.
Jul 20 17:50:00 Nexus systemd[1]: lightdm.service: Failed with result 'e
xit-code'.
Jul 20 17:50:00 Nexus systemd[1]: Failed to start Light Display Manager.



Jul 20 17:49:59 Nexus systemd[1]: lightdm.service: Main process exited, code=exited,
 status=1/FAILURE
░░ Subject: Unit process exited
░░ Defined-By: systemd
░░ Support: https://lists.freedesktop.org/mailman/listinfo/systemd-devel
░░ 
░░ An ExecStart= process belonging to unit lightdm.service has exited.
░░ 
░░ The process' exit code is 'exited' and its exit status is 1.
Jul 20 17:49:59 Nexus systemd[1]: lightdm.service: Failed with result 'e
xit-code'.
░░ Subject: Unit failed
░░ Defined-By: systemd
░░ Support: https://lists.freedesktop.org/mailman/listinfo/systemd-devel
░░ 
░░ The unit lightdm.service has entered the 'failed' state with result 'exit-code'.
Jul 20 17:49:59 Nexus systemd[1]: Failed to start Light Display Manager.
░░ Subject: A start job for unit lightdm.service has failed
░░ Defined-By: systemd
░░ Support: https://lists.freedesktop.org/mailman/listinfo/systemd-devel
░░ 
░░ A start job for unit lightdm.service has finished with a failure.
░░ 
░░ The job identifier is 3561 and the job result is failed.
Jul 20 17:49:59 Nexus systemd[1]: lightdm.service: Scheduled restart job, restart counter is at 4.
░░ Subject: Automatic restarting of a unit has been scheduled
░░ Defined-By: systemd
░░ Support: https://lists.freedesktop.org/mailman/listinfo/systemd-devel
░░ 
░░ Automatic restarting of the unit lightdm.service has been scheduled, as the result f
or
░░ the configured Restart= setting for the unit.
Jul 20 17:49:59 Nexus systemd[1]: Starting Light Display Manager...
░░ Subject: A start job for unit lightdm.service has begun execution
░░ Defined-By: systemd
░░ Support: https://lists.freedesktop.org/mailman/listinfo/systemd-devel
░░ 
░░ A start job for unit lightdm.service has begun execution.
░░ 
░░ The job identifier is 3723.
Jul 20 17:49:59 Nexus systemd[1]: lightdm.service: Main process exited, code=exited,
 status=1/FAILURE

Last edited by Big Scorpio (2025-07-20 15:55:43)

seth · 2025-07-20 21:33:50

1. make sure to keep an open session (ctrl+alt+f3, login, don't log out) so you can inspect the broken system, then see whether it's https://wiki.archlinux.org/title/Securi … n_attempts

Tried switching between the tty terminals (CTRL + ALT + F<number>) but there's not even a video signal present, so i can't log in through the console.

… or use ssh?

2.

Tried using different desktop environment (XFCE) to see if it's not just a Cinnamon issue (?).

And?

3. where do you try to start lightdm? multi-user.target or is there still a GUI session running?
However, SDDM is not what locks your session, that'd be some cinnamon specific screen locker and https://bbs.archlinux.org/viewtopic.php?id=279082 … (there's actually a second thread I'm too lazy to search )

Big Scorpio · 2025-07-22 21:16:16

So it appears to be a cinnamon screenlocker issue (if using Arch?)
I'll have to check it out again when it happens again (deliberately so). I'll follow up.

I can still log in as root and perform commands there. I confirmed its not an SDDM issue. I logged in as root, opened a terminal, changed to my username (su <my username>) and performed a console command with sudo, entered my password and got "wrong password" all 3 times.

seth wrote:

3. where do you try to start lightdm? multi-user.target or is there still a GUI session running?

I don't remember anymore. I found and ran this command "sudo systemctl set-default graphical.target" sometime after but we'll not need to test against LightDM anymore.

seth · 2025-07-22 21:25:17

Most likely https://wiki.archlinux.org/title/Securi … n_attempts and likely triggered somehow™ by the cinnabun screenlocker, yes (since it's OTR for that kind of stuff and you're using it) - unless this also happened on xfce (and no cinnamon-screensaver)

Big Scorpio · 2025-07-25 17:25:55

You're right seth.
I just had this happen again. So i logged in as root and ran this command "faillock --user <username> --reset", then switched user back to my main account and the login was successful.

So what can i do to prevent this from happening in the future? disable cinnamon screenlocker altogether? uninstall it?

edit:

I can try this instruction from you https://bbs.archlinux.org/viewtopic.php … 1#p2065201 let's see ...

Last edited by Big Scorpio (2025-07-25 17:37:21)

seth · 2025-07-25 19:35:11

You'll probably be more lucky w/ disabling faillock, https://bbs.archlinux.org/viewtopic.php … 1#p2247561
Though skimming over https://github.com/linuxmint/cinnamon-s … issues/412 it seems that https://github.com/linuxmint/cinnamon-s … 2017758492 and https://github.com/linuxmint/cinnamon-s … 2018898007 are possibly on the right track and https://github.com/linuxmint/cinnamon-s … 84980makes it sound like this is caused by some very peculiar behavior of that screensaver triggering faillock (and no, that's not a "crappy packaging issue", faillock is now default everywhere)

Arch Linux

#1 2025-07-20 15:45:00

SDDM issue? I can't log in with the correct password after AFKing

#2 2025-07-20 21:33:50

Re: SDDM issue? I can't log in with the correct password after AFKing

#3 2025-07-22 21:16:16

Re: SDDM issue? I can't log in with the correct password after AFKing

#4 2025-07-22 21:25:17

Re: SDDM issue? I can't log in with the correct password after AFKing

#5 2025-07-25 17:25:55

Re: SDDM issue? I can't log in with the correct password after AFKing

#6 2025-07-25 19:35:11

Re: SDDM issue? I can't log in with the correct password after AFKing

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