Upgrading Debian from stretch to buster, and I've had troubles starting xmonad.

What doesn't work

I previously started from the login manager, but now either with gdm3 or lightdm, I get thrown out directly.

Workaround

After I login from a raw console (Ctrl+Alt+F2), I can start xmonad if I create a file ~/.xinitrx and run startx.

What I want

I would like to be able to select xmonad in gdm3, then login, as I used to do in stretch.

I'm using a default minimalist config (works from the console), so I don't think that's the problem.

Please tell me what log files might be relevant to sent!

Logs

/var/log/syslog at the attempt of login:

Aug 13 09:12:24 vinden systemd[1]: session-c8.scope: Killing process 15753 (lightdm) with signal SIGTERM.

Aug 13 09:12:24 vinden systemd[1]: session-c8.scope: Killing process 15756 (lightdm-gtk-gre) with signal SIGTERM.

Aug 13 09:12:24 vinden systemd[1]: session-c8.scope: Killing process 15769 (uim-helper-serv) with signal SIGTERM.

Aug 13 09:12:24 vinden systemd[1]: Stopping Session c8 of user lightdm.

Aug 13 09:12:24 vinden systemd[1]: session-66.scope: Failed to add inotify watch descriptor for control group /user.slice/user-1000.slice/session-66.scope: No space left on device

Aug 13 09:12:24 vinden systemd[1]: Started Session 66 of user gauthier.

Aug 13 09:12:24 vinden at-spi-bus-launcher[8381]: dbus-daemon[8385]: Activating service name='org.a11y.atspi.Registry' requested by ':1.5' (uid=1000 pid=15983 comm="trayer --edge top --align right --SetDockType true")

Aug 13 09:12:24 vinden at-spi2-registr[15994]: Could not open X display

Aug 13 09:12:24 vinden at-spi-bus-launcher[8381]: dbus-daemon[8385]: Successfully activated service 'org.a11y.atspi.Registry'

Aug 13 09:12:24 vinden at-spi-bus-launcher[8381]: SpiRegistry daemon is running with well-known name - org.a11y.atspi.Registry

Aug 13 09:12:24 vinden at-spi2-registr[15994]: AT-SPI: Cannot open default display

Aug 13 09:12:24 vinden dbus-daemon[7613]: [session uid=1000 pid=7613] Activating service name='org.freedesktop.portal.IBus' requested by ':1.22' (uid=1000 pid=15977 comm="/usr/bin/ibus-daemon --daemonize --xim ")

Aug 13 09:12:24 vinden dbus-daemon[7613]: [session uid=1000 pid=7613] Successfully activated service 'org.freedesktop.portal.IBus'

Aug 13 09:12:25 vinden systemd[1]: session-66.scope: Killing process 15897 (lightdm) with signal SIGTERM.

Aug 13 09:12:25 vinden systemd[1]: session-66.scope: Killing process 15903 (gnome-keyring-d) with signal SIGTERM.

Aug 13 09:12:25 vinden systemd[1]: session-66.scope: Killing process 15906 (xmonad-session) with signal SIGTERM.

Aug 13 09:12:25 vinden systemd[1]: session-66.scope: Killing process 15960 (ssh-agent) with signal SIGTERM.

Aug 13 09:12:25 vinden systemd[1]: session-66.scope: Killing process 15977 (ibus-daemon) with signal SIGTERM.

Aug 13 09:12:25 vinden systemd[1]: session-66.scope: Killing process 15988 (ibus-dconf) with signal SIGTERM.

Aug 13 09:12:25 vinden systemd[1]: session-66.scope: Killing process 16007 (dropbox) with signal SIGTERM.

Aug 13 09:12:25 vinden systemd[1]: session-66.scope: Killing process 16008 (dropbox) with signal SIGTERM.

Aug 13 09:12:25 vinden systemd[1]: Stopping Session 66 of user gauthier.

Aug 13 09:12:25 vinden acpid: client 15746[0:0] has disconnected

Aug 13 09:12:25 vinden acpid: client connected from 16014[0:0]

Aug 13 09:12:25 vinden acpid: 1 client rule loaded

Aug 13 09:12:26 vinden systemd[1]: session-c9.scope: Failed to add inotify watch descriptor for control group /user.slice/user-118.slice/session-c9.scope: No space left on device

Aug 13 09:12:26 vinden systemd[1]: Started Session c9 of user lightdm.

Problem solved, but was unrelated. I'll post how I debugged this problem.

I needed to check /var/log/Xorg.0.log, but the file was somehow truncated so that I missed the error.

• login in another tty with Ctrl+Alt+F1.


• save all new input in the log file to a separate file: tail -f /var/log/Xorg.0.log >> ~/tmp/Xorg.log
  


• return to the login manager with Ctrl+Alt+F7.


• attempt to login, in my case it crashed and returned to the login manager.


• return to your other tty with Ctrl+Alt+F1, observe what happened in ~/tmp/Xorg.log.

In my case, if you must know, xkbcomp crashed with a segmentation fault because of an error in my keyboard config file, taking with it the whole thing. I suppose that xkbcomp is a newer version than the one I previously had (because I upgraded Debian), and is less resilient to config errors than the older version.