After upgrading from Ubuntu 17.10 to 18.04 I am not able to login to the desktop environment. This screen shows after restarting:

enter image description here

  • I can only suggest you to backup your data from LiveCD or another Linux installation and to do a clean reinstall. I had the exact same issue and nothing but clean installation solved it.
    – user45853
    Commented May 6, 2018 at 18:05
  • I had the same problem, and I think that doing a sudo mv /etc/X11/xorg.conf /etc/X11/xorg.conf.bak fixed the thing (I also did sudo apt purge nvidia-* and then installed it again, but I don't really know if it changed anything)
    – tforgione
    Commented May 10, 2018 at 14:50

2 Answers 2


Your OS is not properly installed. Try the following:

exec sudo -i
dpkg --configure -a
apt-get -f install
apt-get update
apt-get dist-upgrade
apt-get install --reinstall ubuntu-desktop
apt-get autoremove
apt-get clean

If it doesn't work, reinstall Ubuntu. Follow this to reinstall the OS without loosing data. The post is about Ubuntu 16.04 LTS but it'll also work for Ubuntu 18.04 LTS.

  • In my case this alone did not work, since I was migrating from 17.10 gdm3. As described in the solution of Murmel below, I've got it fixed now by "sudo apt install lightdm" and decide gdm3 as window manager, when the popup appears (gdm3 or lightdm) Commented Aug 20, 2018 at 16:20

In my case

sudo apt install lightdm

solved the problem.

See also:

  • I've been migrating from 17.10 gdm3, Your solution did the trick! I did "sudo apt install lightdm" and decided "gdm3" as window manager, when the popup appeared (gdm3 or lightdm) Commented Aug 20, 2018 at 16:21

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