Arch Linux

gearhead

Member

Registered: 2018-03-24

Posts: 60

[Solved] gdm coredumps with latest system update Jan 11 2026

I updated the system on my laptop yesterday morning and discovered I could not log in via gdm nor could I type in my username and password in a tty. My only access is via ssh.
My 'work around' is to use lightdm which works fine. I had not used it in a long time, but am fine with it as a woprk around, but something is a bit strange with gdm for me.
In another thread, I was asked to provide a full boot log. It is here  BootLog

This laptop has an nvidia chip, but I have nouveau enabled (I do not have the nvidia drivers installed) and it is wayland that I am trying to boot into. It is an old laptop.
The only thing uncommented in /etc/gdm/custom.conf is:

[debug]
# Uncomment the line below to turn on debugging
Enable=true

Please let me know if I can provide more info or help in any way.

Gearhead

Last edited by gearhead (Yesterday 21:28:14)

seth

Member

From: Don't DM me only for attention

Registered: 2012-09-03

Posts: 72,065

Re: [Solved] gdm coredumps with latest system update Jan 11 2026

Jan 12 06:43:32 V550VX kernel: i915 0000:00:02.0: [drm] Found SKYLAKE (device ID 191b) display version 9.00 stepping G0

There's also a GM107M [GeForce GTX 950M] but neither nvidia nor nouveau are being loaded (installing any nvidia-utils package will blacklist nouveau) but your main problem is

Jan 12 06:43:39 V550VX unix_chkpwd[757]: could not obtain user info (gdm-greeter)
Jan 12 06:43:39 V550VX (systemd)[754]: PAM PAM failed: User not known to the underlying authentication module
Jan 12 06:43:39 V550VX (systemd)[754]: user@60578.service: Failed to set up PAM session: Operation not permitted
Jan 12 06:43:39 V550VX (systemd)[754]: user@60578.service: Failed at step PAM spawning /usr/lib/systemd/systemd: Operation not permitted
Jan 12 06:43:39 V550VX systemd[1]: user@60578.service: Main process exited, code=exited, status=224/PAM
Jan 12 06:43:39 V550VX systemd[1]: user@60578.service: Failed with result 'exit-code'.
Jan 12 06:43:39 V550VX systemd[1]: Failed to start User Manager for UID 60578.
Jan 12 06:43:39 V550VX systemd[1]: Started Session 2 of User gdm-greeter.

Probably https://bbs.archlinux.org/viewtopic.php … 5#p2263495  ?

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gearhead

Member

Registered: 2018-03-24

Posts: 60

Re: [Solved] gdm coredumps with latest system update Jan 11 2026

Well, I tried that previously, but must've reverted. I tried it again and now gdm works. Marked as solved
edited these lines in /etc/nsswitch.conf

from
shadow: files

to
shadow: files systemd
gshadow: files systemd