As stated by jokrebel in comment #4, a possible temporary workaround could be to use Gnome (Metacity) desktop session.
1) Press Ctrl + Alt + F1 and login with username and password
2) sudo apt install gnome-session-flashback
3) sudo service lightdm restart
4) Select Gnome (metacity) session and login.
As stated by jokrebel in comment #4, a possible temporary workaround could be to use Gnome (Metacity) desktop session.
1) Press Ctrl + Alt + F1 and login with username and password flashback
2) sudo apt install gnome-session-
3) sudo service lightdm restart
4) Select Gnome (metacity) session and login.