Unable to login to GNOME Shell xorg session while Wayland session works properly

[Farhad Mohammadi Majd]

Hello and thanks in advance for help.

system: Ubuntu 19.04, fully updated, GDM3 only with GNOME Shell,
installed by netinstall image.

GNOME Shell on xorg was working well for weeks, until I installed the
GNOME flashback session (packages: gnome-session-flashback, gnome-
flashback, gnome-flashback-common) or "Applications Menu" the GNOME
Shell extension via GNOME Software from extensions.gnome.org

** I can login to the Wayland session without any problem. **

== logs ==
=== search "shell" in gnome-logs in the tab "All" ===
09:18:07 gnome-shell: JS WARNING:
[resource:///org/gnome/shell/ui/layout.js 23]: reference to undefined
property "MetaWindowX11"

09:18:03 dbus-daemon: [system] Activating via systemd: service
name='org.freedesktop.PackageKit' unit='packagekit.service' requested
by ':1.56' (uid=108 pid=971 comm="/usr/bin/gnome-shell "
label="unconfined")

09:18:03 polkitd: Registered Authentication Agent for unix-session:c3
(system bus name :1.56 [/usr/bin/gnome-shell], object path
/org/freedesktop/PolicyKit1/AuthenticationAgent, locale en_US.UTF-8)

09:18:03 dbus-daemon: [system] Activating via systemd: service
name='org.freedesktop.GeoClue2' unit='geoclue.service' requested by
':1.56' (uid=108 pid=971 comm="/usr/bin/gnome-shell "
label="unconfined")

09:18:03 gnome-shell: g_filename_to_utf8: assertion 'opsysstring !=
NULL' failed

09:18:02 dbus-daemon: [system] Activating via systemd: service
name='org.freedesktop.UPower' unit='upower.service' requested by
':1.56' (uid=108 pid=971 comm="/usr/bin/gnome-shell "
label="unconfined")

09:18:01 gnome-shell: Failed to launch ibus-daemon: Failed to execute
child process ???ibus-daemon??? (No such file or directory)

09:18:01 dbus-daemon: [system] Activating via systemd: service
name='org.freedesktop.locale1' unit='dbus-
org.freedesktop.locale1.service' requested by ':1.56' (uid=108 pid=971
comm="/usr/bin/gnome-shell " label="unconfined")

09:17:54 gnome-session-b: Unrecoverable failure in required component
org.gnome.Shell.desktop

09:17:54 gnome-shell: Failed to create backend: No GPUs found with udev

09:07:49 gnome-session-b: Unrecoverable failure in required component
org.gnome.Shell.desktop

09:07:49 gnome-shell: Failed to create backend: No GPUs found with udev

=== search "shell" in gnome-system-log in the tab "syslog" ===
gnome-shell[634]: Failed to initialize accelerated iGPU/dGPU
framebuffer sharing: No matching EGL configs

gnome-shell[634]: g_dir_open_with_errno: assertion 'path != NULL'
failed

gnome-shell[634]: Failed to get PolKit permission: Polkit.Error:
GDBus.Error:org.freedesktop.PolicyKit1.Error.Failed: Action
org.freedesktop.bolt.enroll is not registered

gnome-shell[634]: Getting invalid resource scale property

gnome-shell[634]: Error checking authorization for action id
org.freedesktop.bolt.enroll:
GDBus.Error:org.freedesktop.PolicyKit1.Error.Failed: Action
org.freedesktop.bolt.enroll is not registered

gnome-shell[634]: Error looking up permission:
GDBus.Error:org.freedesktop.portal.Error.NotFound: No entry for
geolocation

gnome-shell[634]: JS WARNING:
[resource:///org/gnome/shell/ui/windowManager.js 1618]: reference to
undefined property "MetaWindowXwayland"

gnome-shell[609]: Failed to create backend: No GPUs found with udev