Failed to start GNOME Shell on X11 (again)

Problem on desktop PC running Ubuntu 20.04.1

Today, 09/23, I installed the following updates:

2020-09-23 11:28:12 upgrade python3.8-venv:amd64 3.8.2-1ubuntu1.2 3.8.5-1~20.04
2020-09-23 11:28:13 upgrade python3.8-dev:amd64 3.8.2-1ubuntu1.2 3.8.5-1~20.04
2020-09-23 11:28:14 upgrade libpython3.8-dev:amd64 3.8.2-1ubuntu1.2 3.8.5-1~20.04
2020-09-23 11:28:15 upgrade libpython3.8:amd64 3.8.2-1ubuntu1.2 3.8.5-1~20.04
2020-09-23 11:28:16 upgrade python3.8:amd64 3.8.2-1ubuntu1.2 3.8.5-1~20.04
2020-09-23 11:28:17 upgrade python3-distutils:all 3.8.2-1ubuntu1 3.8.5-1~20.04.1
2020-09-23 11:28:18 upgrade libpython3.8-stdlib:amd64 3.8.2-1ubuntu1.2 3.8.5-1~20.04
2020-09-23 11:28:19 upgrade python3.8-minimal:amd64 3.8.2-1ubuntu1.2 3.8.5-1~20.04
2020-09-23 11:28:20 upgrade libpython3.8-minimal:amd64 3.8.2-1ubuntu1.2 3.8.5-1~20.04
2020-09-23 11:28:21 upgrade python3-lib2to3:all 3.8.2-1ubuntu1 3.8.5-1~20.04.1
2020-09-23 11:28:22 upgrade google-chrome-stable:amd64 85.0.4183.102-1 85.0.4183.121-1
2020-09-23 11:28:29 upgrade geogebra-classic:amd64 6.0.604.0-202009091124 6.0.605.0-202009150655
2020-09-23 11:29:20 upgrade busybox-static:amd64 1:1.30.1-4ubuntu6.1 1:1.30.1-4ubuntu6.2
2020-09-23 11:29:21 upgrade python3-gdbm:amd64 3.8.2-1ubuntu1 3.8.5-1~20.04.1
2020-09-23 11:29:22 upgrade busybox-initramfs:amd64 1:1.30.1-4ubuntu6.1 1:1.30.1-4ubuntu6.2
2020-09-23 11:29:23 upgrade gdb:amd64 9.1-0ubuntu1 9.2-0ubuntu1~20.04
2020-09-23 11:29:24 upgrade gdbserver:amd64 9.1-0ubuntu1 9.2-0ubuntu1~20.04
2020-09-23 11:29:25 upgrade mutter-common:all 3.36.4-0ubuntu0.20.04.2 3.36.6-1ubuntu0.20.04.1
2020-09-23 11:29:26 upgrade gir1.2-mutter-6:amd64 3.36.4-0ubuntu0.20.04.2 3.36.6-1ubuntu0.20.04.1
2020-09-23 11:29:27 upgrade libmutter-6-0:amd64 3.36.4-0ubuntu0.20.04.2 3.36.6-1ubuntu0.20.04.1
2020-09-23 11:29:28 upgrade grub2-common:amd64 2.04-1ubuntu26.4 2.04-1ubuntu26.5
2020-09-23 11:29:29 upgrade grub-pc:amd64 2.04-1ubuntu26.4 2.04-1ubuntu26.5
2020-09-23 11:29:29 upgrade grub-pc-bin:amd64 2.04-1ubuntu26.4 2.04-1ubuntu26.5
2020-09-23 11:29:30 upgrade grub-efi-amd64-signed:amd64 1.142.6+2.04-1ubuntu26.4 1.142.7+2.04-1ubuntu26.5
2020-09-23 11:29:32 upgrade grub-efi-amd64-bin:amd64 2.04-1ubuntu26.4 2.04-1ubuntu26.5
2020-09-23 11:29:33 upgrade grub-common:amd64 2.04-1ubuntu26.4 2.04-1ubuntu26.5
2020-09-23 11:29:42 upgrade linux-headers-generic:amd64 5.4.0.48.51 5.4.0.49.52
2020-09-23 11:29:50 upgrade linux-image-generic:amd64 5.4.0.48.51 5.4.0.49.52
2020-09-23 11:29:51 upgrade linux-libc-dev:amd64 5.4.0-48.52 5.4.0-49.53
2020-09-23 11:29:52 upgrade python3-tk:amd64 3.8.2-1ubuntu1 3.8.5-1~20.04.1
2020-09-23 11:29:53 upgrade thermald:amd64 1.9.1-1ubuntu0.2 1.9.1-1ubuntu0.3
2020-09-23 11:29:55 upgrade mutter:amd64 3.36.4-0ubuntu0.20.04.2 3.36.6-1ubuntu0.20.04.1

After that, whenever I turn the monitor off an on again I'm greeted with a blank screen and the message:
"Oh no! Something has gone wrong.
A problem has occurred and the system can't recover.
Please log out and try again."

I'm able to log-in again but the problem persists. Every time I turn on the monitor, the same happens.

So I reproduced the problem and found this on syslog:

ep 23 12:29:56 razorback gnome-shell[3017]: **
Sep 23 12:29:56 razorback gnome-shell[3017]: mutter:ERROR:../src/backends/x11/meta-monitor-manager-xrandr.c:211:meta_monitor_manager_xrandr_update_screen_size: assertion failed: (width > 0 && height > 0 && scale > 0)
Sep 23 12:29:56 razorback gnome-shell[3017]: Bail out! mutter:ERROR:../src/backends/x11/meta-monitor-manager-xrandr.c:211:meta_monitor_manager_xrandr_update_screen_size: assertion failed: (width > 0 && height > 0 && scale > 0)
Sep 23 12:29:57 razorback systemd[1]: Starting Process error reports when automatic reporting is enabled...
Sep 23 12:29:57 razorback whoopsie-upload-all[26630]: /var/crash/_usr_bin_software-properties-gtk.1000.crash already marked for upload, skipping
Sep 23 12:29:57 razorback whoopsie-upload-all[26630]: /var/crash/_usr_bin_gnome-shell.1000.crash already marked for upload, skipping
Sep 23 12:29:57 razorback whoopsie-upload-all[26630]: All reports processed
Sep 23 12:29:57 razorback systemd[1]: apport-autoreport.service: Succeeded.
Sep 23 12:29:57 razorback systemd[1]: Finished Process error reports when automatic reporting is enabled.
Sep 23 12:30:01 razorback CRON[26650]: (root) CMD ([ -x /etc/init.d/anacron ] && if [ ! -d /run/systemd/system ]; then /usr/sbin/invoke-rc.d anacron start >/dev/null; fi)
Sep 23 12:30:03 razorback systemd[2389]: gnome-shell-x11.service: Main process exited, code=dumped, status=6/ABRT
Sep 23 12:30:03 razorback systemd[2389]: gnome-shell-x11.service: Failed with result 'core-dump'.
Sep 23 12:30:03 razorback systemd[2389]: gnome-shell-x11.service: Scheduled restart job, restart counter is at 1.
Sep 23 12:30:03 razorback systemd[2389]: Stopped target GNOME X11 Session (session: ubuntu).
Sep 23 12:30:03 razorback systemd[2389]: Stopping GNOME X11 Session (session: ubuntu).
Sep 23 12:30:03 razorback systemd[2389]: Stopped target GNOME X11 Session.
Sep 23 12:30:03 razorback systemd[2389]: Stopping GNOME X11 Session.
Sep 23 12:30:03 razorback systemd[2389]: Stopped target GNOME Shell on X11.
Sep 23 12:30:03 razorback systemd[2389]: Stopping GNOME Shell on X11.
Sep 23 12:30:03 razorback systemd[2389]: Stopped GNOME Shell on X11.
Sep 23 12:30:03 razorback systemd[2389]: Starting GNOME Shell on X11...
Sep 23 12:30:03 razorback systemd[1]: Starting Process error reports when automatic reporting is enabled...
Sep 23 12:30:03 razorback gnome-shell[26653]: **
Sep 23 12:30:03 razorback gnome-shell[26653]: mutter:ERROR:../src/backends/x11/meta-monitor-manager-xrandr.c:211:meta_monitor_manager_xrandr_update_screen_size: assertion failed: (width > 0 && height > 0 && scale > 0)
Sep 23 12:30:03 razorback gnome-shell[26653]: Bail out! mutter:ERROR:../src/backends/x11/meta-monitor-manager-xrandr.c:211:meta_monitor_manager_xrandr_update_screen_size: assertion failed: (width > 0 && height > 0 && scale > 0)
Sep 23 12:30:03 razorback whoopsie-upload-all[26654]: /var/crash/_usr_bin_software-properties-gtk.1000.crash already marked for upload, skipping
Sep 23 12:30:03 razorback whoopsie-upload-all[26654]: /var/crash/_usr_bin_gnome-shell.1000.crash already marked for upload, skipping
Sep 23 12:30:03 razorback whoopsie-upload-all[26654]: All reports processed
Sep 23 12:30:03 razorback systemd[1]: apport-autoreport.service: Succeeded.
Sep 23 12:30:03 razorback systemd[1]: Finished Process error reports when automatic reporting is enabled.
Sep 23 12:30:03 razorback systemd[2389]: gnome-shell-x11.service: Main process exited, code=dumped, status=6/ABRT
Sep 23 12:30:03 razorback systemd[2389]: gnome-shell-x11.service: Failed with result 'core-dump'.
Sep 23 12:30:03 razorback systemd[2389]: Failed to start GNOME Shell on X11.
Sep 23 12:30:03 razorback systemd[2389]: Dependency failed for GNOME Shell on X11.
Sep 23 12:30:03 razorback systemd[2389]: Dependency failed for GNOME X11 Session.
Sep 23 12:30:03 razorback systemd[2389]: Dependency failed for GNOME X11 Session (session: ubuntu).
Sep 23 12:30:03 razorback systemd[2389]: <email address hidden>: Job <email address hidden>/start failed with result 'dependency'.
Sep 23 12:30:03 razorback systemd[2389]: gnome-session-x11.target: Job gnome-session-x11.target/start failed with result 'dependency'.
Sep 23 12:30:03 razorback systemd[2389]: gnome-shell-x11.target: Job gnome-shell-x11.target/start failed with result 'dependency'.
Sep 23 12:30:03 razorback systemd[2389]: gnome-shell-x11.service: Scheduled restart job, restart counter is at 2.
Sep 23 12:30:03 razorback systemd[2389]: Stopped GNOME Shell on X11.
Sep 23 12:30:03 razorback systemd[2389]: Starting GNOME Shell on X11...
Sep 23 12:30:03 razorback gnome-shell[26684]: **
Sep 23 12:30:03 razorback gnome-shell[26684]: mutter:ERROR:../src/backends/x11/meta-monitor-manager-xrandr.c:211:meta_monitor_manager_xrandr_update_screen_size: assertion failed: (width > 0 && height > 0 && scale > 0)
Sep 23 12:30:03 razorback gnome-shell[26684]: Bail out! mutter:ERROR:../src/backends/x11/meta-monitor-manager-xrandr.c:211:meta_monitor_manager_xrandr_update_screen_size: assertion failed: (width > 0 && height > 0 && scale > 0)
Sep 23 12:30:03 razorback systemd[2389]: gnome-shell-x11.service: Main process exited, code=dumped, status=6/ABRT
Sep 23 12:30:03 razorback systemd[2389]: gnome-shell-x11.service: Failed with result 'core-dump'.
Sep 23 12:30:03 razorback systemd[2389]: Failed to start GNOME Shell on X11.
Sep 23 12:30:03 razorback systemd[2389]: gnome-shell-x11.service: Scheduled restart job, restart counter is at 3.
Sep 23 12:30:03 razorback systemd[2389]: Stopped GNOME Shell on X11.
Sep 23 12:30:03 razorback systemd[2389]: Starting GNOME Shell on X11...
Sep 23 12:30:03 razorback gnome-shell[26699]: **
Sep 23 12:30:03 razorback gnome-shell[26699]: mutter:ERROR:../src/backends/x11/meta-monitor-manager-xrandr.c:211:meta_monitor_manager_xrandr_update_screen_size: assertion failed: (width > 0 && height > 0 && scale > 0)
Sep 23 12:30:03 razorback gnome-shell[26699]: Bail out! mutter:ERROR:../src/backends/x11/meta-monitor-manager-xrandr.c:211:meta_monitor_manager_xrandr_update_screen_size: assertion failed: (width > 0 && height > 0 && scale > 0)
Sep 23 12:30:03 razorback systemd[2389]: gnome-shell-x11.service: Main process exited, code=dumped, status=6/ABRT
Sep 23 12:30:03 razorback systemd[2389]: gnome-shell-x11.service: Failed with result 'core-dump'.
Sep 23 12:30:03 razorback systemd[2389]: Failed to start GNOME Shell on X11.
Sep 23 12:30:03 razorback systemd[2389]: gnome-shell-x11.service: Scheduled restart job, restart counter is at 4.
Sep 23 12:30:03 razorback systemd[2389]: Stopped GNOME Shell on X11.
Sep 23 12:30:03 razorback systemd[2389]: gnome-shell-x11.service: Start request repeated too quickly.
Sep 23 12:30:03 razorback systemd[2389]: gnome-shell-x11.service: Failed with result 'core-dump'.
Sep 23 12:30:03 razorback systemd[2389]: Failed to start GNOME Shell on X11.
Sep 23 12:30:03 razorback systemd[2389]: gnome-shell-x11.service: Triggering OnFailure= dependencies.
Sep 23 12:30:03 razorback systemd[2389]: Started GNOME Session Failed lockdown screen (user).
Sep 23 12:30:03 razorback systemd[2389]: Reached target GNOME Session Failed.
Sep 23 12:30:03 razorback systemd[2389]: Condition check resulted in Disable GNOME Shell extensions after failure being skipped.