After locking screen and monitor going into sleep mode, I can't get the login screen anymore, the monitor stays in sleep mode forever. In previous Ubuntu versions after pressing any key or the mouse, the login screen showed up, but not anymore. I have to restart the computer.

How can I fix this issue?



5 Answers 5


I have already opened a bug report on Launchpad. Please comment there if you have the same problem.



Ubuntu Gnome 16.04.1 + Nvidia graphic drivers: I have the same issue. At the moment a simple workaround is to manually recall the current X window by pressing Ctrl+Alt+F7.

Hope to find a permanent solution soon.

  • 2
    Crtl+Alt+F7 doesn't work with me. I tried all the workarounds I could find online but none works. I'm always stuck with the black screen.
    – blabs
    Sep 25, 2016 at 15:55

Since this is a known bug that needs a patch from the developers, there is no official long-term solution that I know of (although calling dmesg and posting the time-synced results to question might help us to better help you. System boot logs are dmesg's specialty.)

The best I can offer is a workaround. It should work, although I obviously can't test it. It is my goto is situations such as yours, but every situation is unique.

The workaround:

From the black screen, hit [ctrl]+[alt]+[F5] to go to TTY. From there type sudo gnome-session or just gnome-session.

From there, let me know what you see. It should restart the session on TTY1. after that command is correctly entered, use [ctrl]+[alt]+[F1] to return to TTY1. There should be a login screen waiting for you.. no reboot required.

  • Please let me know the result (good or bad) if you decide to use this workaround. There are a lot of other users in the same situation. I do not want to leave any "workarounds that don't work" lying around wasting people's time. : )
    – Nate T
    Sep 4, 2021 at 21:14

I have the same problem now, with Zorin OS 16 (final release), which is based on Ubuntu 20.1, if I'm not wrong.

I hope in'sha'Allah that I'll find a solution for this, or that these bugs would disappear after the next update. You can try installing xsrceensaver, as mentioned by benfischer on Launchpad:

sudo apt install xscreensaver

or you can try updating NVIDIA drivers (you can also remove them and reinstall them) as mentioned by System76.

First run:

sudo apt purge ~nnvidia
sudo apt autoremove
sudo apt clean


sudo apt update
sudo apt full-upgrade
sudo apt install system76-driver-nvidia

After the installation has been completed, run:

sudo systemctl reboot

Now, try logging in again.


I have solved this issue for me by installing lightdm login manager. I have upgraded to Ubuntu 21.10 and after that I have started encountering the blank screen issue while system is locked.

The default Ubuntu login screen is called lightdm. Chances are it's already installed in your system, so you can just run sudo dpkg-reconfigure lightdm to re-select it. If it isn't installed, just run sudo apt-get install lightdm and then follow the commands in the wizard. If you want to uninstall the other login screen (really a display manager), write down the other choices that show up when you run the reconfigure command.

For me gdm3 was already installed, so the istallation wizard wanted to confirm which login manager to use by default, where I choose lightdm.

That's all.

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