I have Ubuntu 16.04.2 LTS, with kubuntu-desktop installed as well as ubuntu-gnome-desktop. The problem is that I cannot switch between Unity, Plasma, and Gnome. When I click the switcher, it does not show any desktop environments and defaults to Gnome. When I try to install Unity, which apparently has been uninstalled, it gives me a "you have held broken packages" error. The login is also quite broken, as it requires multiple tries to log in. In short, I might have irreversibly damaged my computer.
1 Answer
You can set a different default display manager using
sudo dpkg-reconfigure lightdm
(or gmd3, kdm, sddm, etc...)
Changing the default manager should work to restore the switcher functions. It seems lightdm does not like to play well with others.
sudo dpkg-reconfigure lightdm
(or gdm, etc..) and set a default display manager.