Can't change desktop environment

Question

After an automatic update of the kernel on my Ubuntu 16.04 x64 I've lost any possibility to login (login loop problem). So, with Mate env I've solved a nvidia problem and installed Gnome desktop.

After a reboot, I can`t change environment from Mate to Gnome or default Ubuntu. Because whenever I click "env change icon", any buttons showed, till I press Enter. When I just enter my password without changing env, I have Mate desktop.

The question is:

• how to repair login window? Or
• how to set desktop env to default Ubuntu with terminal from Mate?

Answer 1

I had the same problem. I solved it by adding a new user, then "Log Out" and connect again. It shows then the gear icon and you can change the environment.

Answer 2

I had exactly this problem with Ubuntu 16.04. I solved it by installing a number of packages:

desktop-base
gnome-themes-standard
gnome-themes-standard-data
lightdm-gtk-greeter 
lightdm-gtk-greeter-settings
unity-greeter-badges

I also reinstalled: ubuntu-desktop and ubuntu-settings, but I don't think that was necessary. I now get a different login screen, but can choose the desktop environment from the top panel (drop down menu).

Answer 3

Selecting and Deselecting the "High Contrast Text" option in the menu that appears on clicking the top right 'gear' icon seems to solve the problem temporarily for me on Xenial. But you need to do this each time you log in.