Ubuntu – Can’t lock screen with shortcut on Ubuntu 20.04 gnome


In shortcuts i have Super + L for locking screen. But on pressing it – nothing happens. In syslog:

gsd-media-keys[1979]: Couldn't lock screen: Cannot invoke method; 
proxy is for the well-known name org.gnome.ScreenSaver without an owner, and proxy was constructed with the G_DBUS_PROXY_FLAGS_DO_NOT_AUTO_START flag

Locking from interface works fine.

System info: Ubuntu 19.04 upgraded to 20.04

Linux laptop 5.4.0-21-generic #25-Ubuntu SMP Sat Mar 28 13:10:28 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux

No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 20.04 LTS
Release:    20.04
Codename:   focal

GNOME Shell 3.36.1

Other info:

gsettings get org.gnome.desktop.screensaver lock-enabled = true
gsettings get org.gnome.desktop.lockdown disable-lock-screen = false

gnome-screensaver 3.6.1

I also tried: gnome-screensaver-command -l but nothing happens.

I already tried to reinstall gnome-shell and gnome-screensaver – it didn't help.

How to fix locking screen from hotkey?

Best Answer

  • My original question was banned as bug, but it isn't a bug - it's a wrong configuration. People faced this problem a lot in the internet and SO:

    In my case I was using lightdm and screen lock is disabled in it due security issues. Read more here

    You can check you display manager with: sudo systemctl status display-manager

    If you still want to lock your screen with lightdm - you can use dm-tool lock. Also you can add it to keyboard shortcut as command (e.g. Super+L).

    Switching to gdm3 helped: sudo dpkg-reconfigure gdm3

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