Bug#1094353: live-config: Autologin not honored with LightDM/Plasma 6 on Trixie(testing)

[Roland Clobus]

Hello Arjen,

On 04/02/2025 09:37, Arjen Balfoort wrote:

I wanted to check the order of systemd processes:
systemd-analyze dot --order | dot -Tsvg > systemd.svg

That showed me that live-config starts early in the boot process and lightdm a lot later. So, I assume that live-config already finished writing the lightdm configuration far before lightdm is started. I think that lightdm tries to autologin and gets thrown back immediately. I don't know why, but I think that I have to report this with the lightdm devs.

I've looked at 'journalctl -xe'.
The following entries look suspicious:
-- start --

Feb 05 18:38:26 solydxk pulseaudio[1821]: X11 I/O error handler called

-- stop --

Feb 05 18:38:26 solydxk lightdm[1703]: Failed to write utmpx: No such file or directory Feb 05 18:38:26 solydxk lightdm[1703]: pam_unix(lightdm:session): session closed for user solydxk Feb 05 18:38:26 solydxk systemd-logind[1332]: Session 2 logged out. Waiting for processes to exit. Feb 05 18:38:26 solydxk pulseaudio[1821]: X11 I/O error exit handler called, preparing to tear down X11 modul> Feb 05 18:38:26 solydxk kwin_x11[1990]: The X11 connection broke: I/O error (code 1) Feb 05 18:38:26 solydxk kwin_x11[1990]: XIO: fatal IO error 2 (No such file or directory) on X server ":0" Feb 05 18:38:26 solydxk kwin_x11[1990]: after 13671 requests (13645 known processed) with 0 events rema> Feb 05 18:38:26 solydxk systemd[1799]: Stopped plasma-kded6.service - KDE Daemon 6. The error message is generated by lightdm (https://sources.debian.org/src/lightdm/1.32.0-6/src/session-child.c/?hl=757#L757)

Additionally I've looked in ~/.xsession-errors:
In the 2025 image the following 3 lines are present:
-- start --

localuser:solydxk being added to access control list
/etc/X11/Xsession: 5: /etc/profile.d/sbin.sh: [[: not found
-- stop --

The second line is not present when the 2024 image is started.


And a third thing: 'grep XDG_ ~/.xession-errors':

I'm not sure if that was the intended effect.

And looking at /var/log/lightdm/seat0-greeter.log:
-- start --

-- stop --

The file exists, but is a dangling symlink.

I hope this helps you to find the cause for the missing autologin.

With kind regards,
Roland Clobus

The file /var/log/wtmp will not be generated at runtime for the 2024 image you prepared, but in the 2025 image it is generated. dbus-update-activation-environment: setting XAUTHORITY=/home/solydxk/.Xauthority You might take a look at the error message in the third line, which is logged for both images (but this is probably not in scope of this bug report). The XDG_SESSION_TYPE changed from 'wayland' to 'x11', and XDG_SESSION_DESKTOP changed from 'plasmaywayland' to 'lightdm-xsession'. Failed to load session file /usr/share/xsessions/kde-plasma-kf5.desktop: No such file or directory

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