A Ubuntu 20.04 system has its monitors automatically turned off after 30 minutes. However, there is this one time where pressing some keyboard keys no longer turn the monitor back on to show the login screen.
Tried connecting to the machine via SSH from another system, but it appears that SSH server is no longer responding to SSH requests nor pings.
How do we find out the reason for this freezing?
Looked into /var/log/syslog and below are the messages right around the time of the freeze/crash and after the system was manually rebooted.
Apr 30 14:08:53 x-pc kernel: [144091.494964] audit: type=1400 audit(1619806133.342:99): apparmor="DENIED" operation="open" profile="snap.snap-store.ubuntu-software" name="/var/lib/snapd/hostfs/usr/share/gdm/greeter/applications/gnome-initial-setup.desktop" pid=3610 comm="snap-store" requested_mask="r" denied_mask="r" fsuid=1000 ouid=0
Apr 30 14:08:53 x-pc kernel: [144091.938048] audit: type=1400 audit(1619806133.782:100): apparmor="DENIED" operation="open" profile="snap.snap-store.ubuntu-software" name="/var/lib/snapd/hostfs/usr/share/gdm/greeter/applications/gnome-initial-setup.desktop" pid=3610 comm="snap-store" requested_mask="r" denied_mask="r" fsuid=1000 ouid=0
Apr 30 14:08:54 x-pc kernel: [144092.311141] audit: type=1326 audit(1619806134.158:101): auid=1000 uid=1000 gid=1000 ses=3 subj=snap.snap-store.ubuntu-software pid=3610 comm="snap-store" exe="/snap/snap-store/518/usr/bin/snap-store" sig=0 arch=c000003e syscall=93 compat=0 ip=0x7fa31b27c4e7 code=0x50000
Apr 30 14:08:54 x-pc dbus-daemon[3131]: apparmor="DENIED" operation="dbus_method_call" bus="session" path="/org/gtk/Notifications" interface="org.gtk.Notifications" member="RemoveNotification" mask="send" name="org.gtk.Notifications" pid=3610 label="snap.snap-store.ubuntu-software" peer_pid=3346 peer_label="unconfined"
Apr 30 14:08:54 x-pc dbus-daemon[3131]: apparmor="DENIED" operation="dbus_method_call" bus="session" path="/org/gtk/Notifications" interface="org.gtk.Notifications" member="RemoveNotification" mask="send" name="org.gtk.Notifications" pid=3610 label="snap.snap-store.ubuntu-software" peer_pid=3346 peer_label="unconfined"
Apr 30 14:16:06 x-pc dbus-daemon[3131]: [session uid=1000 pid=3131] Activating via systemd: service name='org.freedesktop.Tracker1' unit='tracker-store.service' requested by ':1.2' (uid=1000 pid=3127 comm="/usr/libexec/tracker-miner-fs " label="unconfined")
Apr 30 14:16:06 x-pc systemd[3119]: Starting Tracker metadata database store and lookup manager...
Apr 30 14:16:07 x-pc dbus-daemon[3131]: [session uid=1000 pid=3131] Successfully activated service 'org.freedesktop.Tracker1'
Apr 30 14:16:07 x-pc systemd[3119]: Started Tracker metadata database store and lookup manager.
Apr 30 14:16:41 x-pc tracker-store[147368]: OK
Apr 30 14:16:41 x-pc systemd[3119]: tracker-store.service: Succeeded.
Apr 30 14:17:02 x-pc CRON[147391]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Apr 30 14:46:58 x-pc systemd-modules-load[537]: Inserted module 'lp'
Apr 30 14:46:58 x-pc systemd-modules-load[537]: Inserted module 'ppdev'
Apr 30 14:46:58 x-pc systemd-modules-load[537]: Inserted module 'parport_pc'
Apr 30 14:46:58 x-pc systemd-sysctl[561]: Not setting net/ipv4/conf/all/promote_secondaries (explicit setting exists).
Apr 30 14:46:58 x-pc systemd-sysctl[561]: Not setting net/ipv4/conf/default/promote_secondaries (explicit setting exists).
Apr 30 14:46:58 x-pc systemd[1]: Starting Flush Journal to Persistent Storage...
Apr 30 14:46:58 x-pc systemd[1]: Started udev Kernel Device Manager.
Apr 30 14:46:58 x-pc systemd[1]: Finished Monitoring of LVM2 mirrors, snapshots etc. using dmeventd or progress polling.
Apr 30 14:46:58 x-pc mtp-probe: checking bus 3, device 3: "/sys/devices/pci0000:00/0000:00:01.2/0000:20:00.0/0000:21:08.0/0000:2a:00.3/usb3/3-5"
Apr 30 14:46:58 x-pc systemd[1]: Reached target Local File Systems (Pre).
Apr 30 14:46:58 x-pc mtp-probe: bus: 3, device: 3 was not an MTP device
Apr 30 14:46:58 x-pc systemd[1]: Mounting Mount unit for canonical-livepatch, revision 97...
Apr 30 14:46:58 x-pc mtp-probe: checking bus 3, device 2: "/sys/devices/pci0000:00/0000:00:01.2/0000:20:00.0/0000:21:08.0/0000:2a:00.3/usb3/3-2"
Apr 30 14:46:58 x-pc systemd[1]: Mounting Mount unit for canonical-livepatch, revision 98...
Apr 30 14:46:58 x-pc systemd[1]: Mounting Mount unit for code, revision 61...
Apr 30 14:46:58 x-pc systemd[1]: Mounting Mount unit for code, revision 62...
Apr 30 14:46:58 x-pc systemd[1]: Mounting Mount unit for core, revision 10908...
Apr 30 14:46:58 x-pc kernel: [ 0.000000] Linux version 5.8.0-50-generic (buildd@lgw01-amd64-030) (gcc (Ubuntu 9.3.0-17ubuntu1~20.04) 9.3.0, GNU ld (GNU Binutils for Ubuntu) 2.34) #56~20.04.1-Ubuntu SMP Mon Apr 12 21:46:35 UTC 2021 (Ubuntu 5.8.0-50.56~20.04.1-generic 5.8.18)
Apr 30 14:46:58 x-pc kernel: [ 0.000000] Command line: BOOT_IMAGE=/boot/vmlinuz-5.8.0-50-generic root=UUID=8686a110-298e-49e7-8509-15fca1f29b59 ro quiet splash vt.handoff=7
Apr 30 14:46:58 x-pc kernel: [ 0.000000] KERNEL supported cpus:
Apr 30 14:46:58 x-pc systemd[1]: Mounting Mount unit for core, revision 10958...
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