I also confirmed that removing gnome-calendar was not enough. I had to remove gir1.2-mutter-10, which removed gdm3 (and thus ubuntu-desktop) to be able to run do-release-upgrade until the end.
I also confirmed that removing gnome-calendar was not enough.
I had to remove gir1.2-mutter-10, which removed gdm3 (and thus ubuntu-desktop) to be able to run do-release-upgrade until the end.