When I configure gdm as my default display manager (dpkg-reconfigure gdm3) and then reboot, I get a black screen with a blinking cursor. From there, I cannot do anything since the ttys does not work (ctrl+alt+F1 to F7). I could not figure out why.

In order to resolve this issue, I boot into safe mode, reconfigure lightdm and then reboot.

I observed that gdm could not start for some reason (hence the black screen).

$ systemctl status gdm.service 
● gdm.service - GNOME Display Manager
   Loaded: loaded (/lib/systemd/system/gdm.service; static; vendor preset: enabled)
   Active: inactive (dead)

Nov 04 16:46:05 rigel systemd[1]: gdm.service: Unit cannot be reloaded because it is inactive.

When I manually start gdm systemctl status gdm.service I am able to logout and log back in using gdm. After reboot, the black screen occurs again with the blinking cursor.

Any ideas? Thanks.

GNOME Shell 3.30.1
Ubuntu 18.10 cosmic
Kernel: x86_64 Linux 4.18.0-10-generic
NVIDIA driver 410.73 (GeForce GTX 970)
  • How old is this computer? Laptop or desktop? Video card? Does it boot if you set nomodeset in the kernel boot line in GRUB? – heynnema Nov 4 '18 at 23:45
  • @heynnema Thanks for the suggestion. The computer is a desktop (not old, about 3 years). My video card is Nvidia GeForce GTX 970. I tried the nomodeset flag in GRUB but I got the same error. – jimouris Nov 5 '18 at 12:29
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    You could try reinstalling gdm3. Maybe the update didn't complete. sudo apt-get update and sudo apt-get install --reinstall gdm3. Then sudo dpkg-reconfigure gdm3 and reboot. – heynnema Nov 5 '18 at 13:05
  • I have also tried that, did not work. – jimouris Nov 5 '18 at 14:12
  • Update: Disabling Wayland and reinstalling ubuntu-session fixed the issue, as @adrinux suggested. – jimouris Nov 28 '18 at 11:31

I had the same problem on both my Ubuntu 18.04 boxes after upgrade to 18.10. Both are configured with nvidia grahpics and to use the vanilla gnome session Ubuntu provides (not the Unity-ish version they munged together). Much faffing with nvidia drivers had no effect.

I did two other things - not sure which brought it back. From this answer Edit /etc/gdm3/custom.conf as a sudo and uncomment the line to force Xorg over Wayland


I also installed ubuntu-session:

sudo apt install ubuntu-session

But not sure whether that is really required so I suggest you try editing /etc/gdm3/custom.conf and rebooting first.


  • Thanks!! I have tried to disable Wayland WaylandEnable=false (I saw it in the same answer as you), but it had not worked. However, reinstalling ubuntu-session fixed the problem. – jimouris Nov 28 '18 at 11:21
  • Out if interest did you revert that change to WaylandEnable=false before reinstalling ubuntu-session? – adrinux Nov 29 '18 at 12:48
  • Yes, I first disabled Wayland and then reinstalled ubuntu-session. – jimouris Nov 29 '18 at 12:51
  • For me reinstalling ubuntu-session worked. No need to disable wayland. The problem started after upgrade from 18.10 to 19.04. – knoftrix Aug 8 '19 at 16:40

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