I am sporadically experiencing reboots when my screen is locked. Until now, no unwanted reboots or freezes happened when the screen was unlocked. When the problem occurs, the system freezes, which is audible when music is playing in the background (gets stuck in a loop). From there on, the screen remains black and does not wake through keyboard/mouse input. After some time, boot messages appear, signalizing that a reboot has happened. I am unable to properly reproduce the problem. Sometimes the system is locked for hours, then I can wake it and I can log in, sometimes it freezes/reboots.
$ uname -r
5.15.0-50-generic
$ echo $XDG_SESSION_TYPE
wayland
In despair, I have tried switching to wayland as the issue also occurred with x11. Did not work.
To me, the system journal does not indicate any critical issues. Here, the last five minutes from before the issue happened the last time today:
$ sudo journalctl -b -1 -e
[...]
Oct 17 15:17:01 (timestamp of this message just for reference)
Oct 17 15:21:22 system_hostname audit[830]: AVC apparmor="ALLOWED" operation="open" profile="/usr/sbin/sssd" name="/proc/703/cmdline" pid=830 comm="sssd_nss" requested_mask="r" denied_mask="r" fsuid=0 ouid=0
Oct 17 15:21:22 system_hostname kernel: audit: type=1400 audit(1666012882.868:1033): apparmor="ALLOWED" operation="open" profile="/usr/sbin/sssd" name="/proc/703/cmdline" pid=830 comm="sssd_nss" requested_mask>
Oct 17 15:21:32 system_hostname gnome-shell[6058]: cr_parser_new_from_buf: assertion 'a_buf && a_len' failed
Oct 17 15:21:32 system_hostname gnome-shell[6058]: cr_declaration_parse_list_from_buf: assertion 'parser' failed
Oct 17 15:21:32 system_hostname gnome-shell[6058]: cr_parser_new_from_buf: assertion 'a_buf && a_len' failed
Oct 17 15:21:32 system_hostname gnome-shell[6058]: cr_declaration_parse_list_from_buf: assertion 'parser' failed
Oct 17 15:21:32 system_hostname gnome-shell[6058]: g_dbus_connection_emit_signal: assertion 'G_IS_DBUS_CONNECTION (connection)' failed
Oct 17 15:21:32 system_hostname gnome-shell[6058]: cr_parser_new_from_buf: assertion 'a_buf && a_len' failed
Oct 17 15:21:32 system_hostname gnome-shell[6058]: cr_declaration_parse_list_from_buf: assertion 'parser' failed
Oct 17 15:21:33 system_hostname update-notifier[7118]: gtk_widget_get_scale_factor: assertion 'GTK_IS_WIDGET (widget)' failed
Oct 17 15:21:54 system_hostname sssd_pac[2206]: Shutting down
Oct 17 15:21:54 system_hostname systemd[1]: sssd-pac.service: Succeeded.
Oct 17 15:23:09 system_hostname ubuntu-report[4393]: level=error msg="data were not delivered successfully to metrics server, retrying in 960s"
The next log I get is from the reboot at Oct 17 15:24:41.
I have also checked for memory problems using memtester - everything OK.
I would be grateful for any help or suggestions what to look into next.
EDIT 1:
The issue also occurs when never logging in. Over night, the system rebooted multiple times, without any user interaction.
