Can't lock screen when using lightdm with gnome-shell

[Brian Murray]

Trying to use Super+L or Ctrl+Alt+L, I cannot lock the screen. Additionally, if I wait a very long time the screen does not lock either.

Switching from LightDM to GDM3 fixes the issue.

ProblemType: Bug
DistroRelease: Ubuntu 17.10
Package: gnome-shell 3.25.91-0ubuntu3
ProcVersionSignature: Ubuntu 4.12.0-12.13-generic 4.12.8
Uname: Linux 4.12.0-12-generic x86_64
ApportVersion: 2.20.7-0ubuntu1
Architecture: amd64
CurrentDesktop: GNOME
Date: Wed Sep 6 09:17:35 2017
DisplayManager: lightdm
InstallationDate: Installed on 2016-01-22 (592 days ago)
InstallationMedia: Ubuntu 16.04 LTS "Xenial Xerus" - Alpha amd64 (20160117)
SourcePackage: gnome-shell
UpgradeStatus: No upgrade log present (probably fresh install)

[Brian Murray (brian-murray)]

Using the lock icon in the upper right corner did work though.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Janne Snabb (snabb)]

I am using gdm3 (AFAIK) and super-L also stopped working just now when I did "apt dist-upgrade". So in my case it does not seem to depend on lightdm vs gdm3.

[Janne Snabb (snabb)]

In my case I was able to workaround this issue by changing the lock shortcut from super-L to ctrl-alt-L. All shortcuts using super are broken. My "window action key" in gnome-tweaks is "super". So it appears that it is impossible to use the window action key for shortcuts any more after some very recent updata.

[Jérôme Steunou (jsteunou)]

Same issue after an upgrade from 17.04

* I was using lightdm and ctrl+alt+L
* After upgrade I was on gdm (oO ok~~~) Neither ctrl+alt+L or super+L worked
* I switched to lightdm and changed shortcut from ctrl+alt+L to super+L and it works, hurray! I'm keeping it but meh...

[Tiago (timotta)]

Ubuntu 18 is still with the same bug

[Anders Hall (a.hall)]

Confirm (Super - L) not working on Ubuntu 18.04, switching keyboard language does not work either most of the time (Super + Space). Those I use the most. Extremely annoying after some time, especially when using dual screens (since the Gnome top bar is only on one monitor which is even more annoying: https://bugs.launchpad.net/ubuntu/+source/gnome-shell/+bug/1682542).

Worked fine in Ubuntu 17.10 with Gnome and previous versions with Unity.

[Anders Hall (a.hall)]

Sorry, small adjustment. I use wayland as default since 17.10 with gdm (works well in general for me):

loginctl show-session c1 -p Type
Type=wayland

[Christian Geiger (chris-18)]

I had the same problem on ubuntu 18.04. Disabling the key "/org/gnome/desktop/lockdown/disable-lock-screen" in dconf-editor solved the problem.

[Andrew Schulman (z-ubuntuone-andrex)]

> Disabling the key "/org/gnome/desktop/lockdown/disable-lock-screen" in dconf-editor solved the problem.

I'm not sure what you mean by disabling. If you mean set it to false, false is already the default value. It was at its default for me. I tried overriding it and setting it to false, but that didn't help. So this solution doesn't work for me.

[Christian Geiger (chris-18)]

Yes, I mean set it to false. I have made an upgrade from 16.04. Maybe the key wasn't on its default value before the upgrade. But on ubuntu 16.04 I didn't have this problem.

[Dmytro Korzhevin (korg)]

> Disabling the key "/org/gnome/desktop/lockdown/disable-lock-screen" in dconf-editor solved the problem.

Also, solved for mee too (Ubuntu 18.10 with all updates installed, per 12 Dec 2018)

[Cristian Balan (oviliz)]

Any news here? :(

If helps, I've also upgraded from Xenial long time ago.

[Jason Jystad (jystadj)]

Just ran into this issue on a fresh install of 19.10 with all updates installed as of 2019/11/30. The lock icon in the menu is missing and the keyboard shortcut is non-functional. The Screen Lock dialog in settings is greyed out entirely.

chris-18's fix from earlier worked.

Setting org/gnome/desktop/lockdown/disable-lock-screen to disabled: enabled the icon, the keyboard shortcut, and the Screen Lock dialog in settings.

[Daniel van Vugt (vanvugt)]

Bug 1851992 has been opened about the disable-lock-screen option too. But it's private for now.

[Brian Neltner (neltnerb)]

The fix provided by chris-18 worked for me, same issue.

[Rocko (rockorequin)]

My Ubuntu 20.04 installation just did this - something changed the org.gnome.desktop.lockdown disable-lock-screen to true and also the blank screen to never (did an update do this?).

But there's nothing I can see in gnome-control-center to modify this value, making this bug pretty obscure when it happens. Wouldn't a setting in g-c-c make a lot of sense if you can actually disable the screen lock completely?

[Daniel van Vugt (vanvugt)]

Rocko, that is probably bug 1851992 and not this one. This one is about lightdm.

[Jose (jvel)]

I managed to fix it in the following way:

1. Install dconf-editor (to edit the "registry keys")
sudo apt install dconf-editor

2. Open dconf-editor as a normal app; search for: /org/gnome/desktop/lockdown/

3. In my case, the disable-lock-screen was set turned on. I turned it off and everything now works fine!