Every time I try to kill the x-server,

sudo service lightdm stop

so that I can install the latest Nvidia drivers, I get an error message.

stop: Unknown instance:

What am I doing wrong?

  • 1
    that depends on which DM you are using: sudo service lightdm stop --> Ubuntu with Unity; sudo service kdm stop --> Kubuntu; sudo service gdm stop ..; Jul 18, 2013 at 13:02

6 Answers 6

  1. Use Ctrl+Alt+F1 to switch to TTY.

  2. Log in.

  3. Run:

    sudo service lightdm stop

    LightDM and Xserver should be stopped now (check with Ctrl+Alt+F7, which is your current Xorg session, it should not show any desktop now).

  4. Do your things.

  5. Run the following command to start lightdm and xorg again:

    sudo service lightdm start

Good Luck!

  • 5
    That's exactly what I did except halfway through #3 I was stopped with an error message. Jul 16, 2013 at 13:59
  • 4
    That sounds mysterious ;) my best guess is that lightdm is not runnig at all and you are using some other Display manger... With cat /etc/X11/default-display-manager, you can find out which Display Manager you are currently using, with sudo service --status-all you can find out which services are currently running. Maybe that helps to find out why there is no lightdm instance and what Diplay manager runs instead..
    – mondjunge
    Jul 16, 2013 at 14:16
  • 1
    For me it was gdm3 rather than lightdm. Also my desktop environment in recent ubuntu was running on the F1 terminal, not F7, so I did the sudo service gdm3 stop on some other free terminal - the F3 one.
    – Klesun
    Sep 26, 2021 at 10:20

I did a little more digging around and found that I could just use pgrep to find its PID and then kill it.

pgrep dm -l

sudo kill (insert PID here)

  • 4
    I think this is a bit dangerous. You could kill the RAID software manager (mdadm).
    – Spiros
    Mar 17, 2017 at 15:42

You will need the help of htop or top. Write down the PID number of the process you want to kill (in this case, Xorg). Once you have the PID, run the below command in a root shell (sudo -s):

kill -9 <PID>

For example:

kill -9 1234

You should then be able to install the NVidia drivers.

  • Thanks! actually realized this and started typing while you answered. Jul 16, 2013 at 14:25
  • Do you have nvidia-card with CUDA ? - for this case there is special driver - you can read all this at my post here : askubuntu.com/questions/311151/… Jul 16, 2013 at 14:29

Try running sudo service gdm stop.

The reason your command may be resulting in that output is because lightdm isn't your Display Manager.

In addition to gdm, also try xdm and kdm.


/etc/init.d/lightdm stop maybe? And why you can't install nvidia drivers from software center?

  • 1
    They're outdated, the NVIDIA website always has the most recent drivers. Jul 16, 2013 at 14:00

Ok had the GTX 970 installation Problem under Ubuntu 14.04 too. Sometime i was able to start Ubuntu with the standart drivers and sometime not.

However, this should hopefully fix the Problem: After switching from IGP (I7 4770 with HD4600) to GTX970 in Biosi got an error with some Xorg Gui.

However you can not install the Nvidia-Driver while X is running: -> sudo killall Xorg solves the problem

Then -> sudo ./NVIDIA-x68xxx.run

After the first Driver Install (orig. Nvidia 352.xx) i had a blank screen. Then i run the Nvidia Driver Installer again -> sudo ./NVIDIA-x68xxx.run This second install told me some kind of noveu driver is running and should be disabled. The driver asked me if it should disable noveu -> Yes disable noveu

After restart: Et Voila lighdm is running again :)

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