Cannot run Ubuntu 18.04 on Xorg
Solution 1:
I had to uncomment 'WaylandEnable=false' in /etc/gdm3/custom.conf to be able to boot up. It worked, but I'd like to find a better fix for the situation. Booting up with 'WaylandEnable=false' commented out I would get stuck at gdm.servicegdm.service.
I hope this helps someone, I looked for this for a couple weeks.