I can successfully login with lightdm after deleting every Xorg session entries correpsonding to a wayland session entry (ex rm /usr/share/xessions/gnome /usr/share/xessions/ubuntu and leave /usr/share/wayland-sessions/gnome and /usr/share/wayland-sessions/ubuntu).
I can successfully login with lightdm after deleting every Xorg session entries correpsonding to a wayland session entry (ex rm /usr/share/ xessions/ gnome /usr/share/ xessions/ ubuntu and leave /usr/share/ wayland- sessions/ gnome and /usr/share/ wayland- sessions/ ubuntu) .