In my case, the problem started after turning on WebGL Couds theme and was resolved by switching back to the regular Clouds theme. However, I first had to remove MDM and install GDM via a tty terminal. After logging in with GDM I was able to re-install MDM and change the theme back to regular Clouds.
In my case, the problem started after turning on WebGL Couds theme and was resolved by switching back to the regular Clouds theme. However, I first had to remove MDM and install GDM via a tty terminal. After logging in with GDM I was able to re-install MDM and change the theme back to regular Clouds.