After upgrading to 18.04 from 16.04 I get a login screen which looks complete but typing in my password gives the error failed to start session
.
I can use Ctrl+Alt+F1 to access tty where logging in is successful but starting almost immediately terminates.
I have read similar solutions about installing ubuntu-session but attempting these gives unable to correct problems, you have held broken packages
with the dependencies on gnome-shell and gnome-session-bin listed as unmet dependencies.