screen locking doesn't work when using lightdm

[Rick T]

I upgraded from 18.04 to 20.04.1 and the screen doesn't lock or go blank at the set time. I think this issue also effects the shortcuts not working also.

I'm using nemo as my file manager I followed these instructions below

https://itsfoss.com/install-nemo-file-manager-ubuntu/

[Rick T (ratulloch)]

rt@sys76:~$ uname -a
Linux sys76 5.4.0-48-generic #52-Ubuntu SMP Thu Sep 10 10:58:49 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux

[Ubuntu Foundations Team Bug Bot (crichton)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. It seems that your bug report is not filed about a specific source package though, rather it is just filed against Ubuntu in general. It is important that bug reports be filed about source packages so that people interested in the package can find the bugs about it. You can find some hints about determining what package your bug might be about at https://wiki.ubuntu.com/Bugs/FindRightPackage. You might also ask for help in the #ubuntu-bugs irc channel on Freenode.

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[Rick T (ratulloch)]

The options for locking, blanking and shortcut keys are in the gnome-control-center

[Sebastien Bacher (seb128)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. Unfortunately, we cannot work on this bug because your description didn't include enough information. You may find it helpful to read "How to report bugs effectively" http://www.chiark.greenend.org.uk/~sgtatham/bugs.html. We'd be grateful if you would then provide a more complete description of the problem.

We have instructions on debugging some types of problems at http://wiki.ubuntu.com/DebuggingProcedures.

At a minimum, we need:

1. The specific steps or actions you took that caused you to encounter the problem.
2. The behavior you expected.
3. The behavior you actually encountered (in as much detail as possible).

Please also ensure that you include the release and flavour of Ubuntu that you are using.

Thank you!

[Sebastien Bacher (seb128)]

The description isn't clear, it doesn't lock at the same time than what? Also what has the filemanager having to do with the issue?

[Rick T (ratulloch)]

1. The specific steps or actions you took that caused you to encounter the problem.

-I tried to set the screen to lock at a specific interval and it doesn't lock
Settings-> Privacy-> Screen Lock -> Automatic Screen Lock -> Enabled
Settings-> Privacy-> Screen Lock -> Automatic Screen Lock -> 30 seconds

-The screen doesn't go blank at all (option found under)
Settings-> Privacy-> Screen Lock -> Blank screen Delay -> 1 minute

2. The behavior you expected.
It should lock the screen and have the screen go blank but it doesn't

3. The behavior you actually encountered (in as much detail as possible).
Nothing happens the screen doesn't lock or goes blank.

Please also ensure that you include the release and flavour of Ubuntu that you are using.
I upgraded from 18.04 to 20.04.1 using the sotware updater GUI
rt@sys76:~$ uname -a
Linux sys76 5.4.0-48-generic #52-Ubuntu SMP Thu Sep 10 10:58:49 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux

About me including the file-manager being nemo I was just trying to include everything I could think of to help out.

If you need anything else let me know.

[Rick T (ratulloch)]

Should be:
Settings-> Privacy-> Screen Lock -> Automatic Screen Lock Delay -> 30 seconds

[Sebastien Bacher (seb128)]

Could you add your 'journalctl -b 0' log after getting the issue? can you manually lock the screen from the indicator or using the keybinding?

[Rick T (ratulloch)]

Sure

The Keyboard Shortcuts for Lock Screen is set to Ctrl+Alt+L
Found in Settings -> Keyboard Shortcuts -> Lock screen -> Ctrl+Alt+L

1) I can't lock the screen using the (keybinding / shortcut) Ctrl+Alt+L
https://i.imgur.com/VKiXvZV.png

2) I can lock the screen by clicking on the lock option but the screen doesn't go blank
https://i.imgur.com/JDHEs2Q.png

3) Here's something that looks interesting I found in the journalctlr file
Oct 02 19:18:52 sys76 gnome-shell[2577]: meta_window_raise: assertion '!window->override_redirect' failed
Oct 02 19:18:52 sys76 gnome-shell[2577]: meta_window_lower: assertion '!window->override_redirect' failed
Oct 02 19:18:56 sys76 gsd-media-keys[2742]: 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

4) The full file is below

[Daniel van Vugt (vanvugt)]

Rick, what do you get if you run this command?

gsettings get org.gnome.desktop.lockdown disable-lock-screen

[Rick T (ratulloch)]

I get false

rt@sys76:~$ gsettings get org.gnome.desktop.lockdown disable-lock-screen
false

[Rick T (ratulloch)]

I switched display managers from lightdm to gdm and it fixed the issue

sudo systemctl status display-manager

sudo dpkg-reconfigure lightdm

systemctl status gdm.service

sudo apt install --reinstall ubuntu-session

reboot machine

Info about the issue:
https://bbs.archlinux.org/viewtopic.php?id=150017

https://askubuntu.com/questions/1245071/cant-lock-screen-with-shortcut-on-ubuntu-20-04-gnome

[Daniel van Vugt (vanvugt)]

Please merge this with the similar bugs like bug 1864982, bug 1853709, bug 1812556 and more...

https://bugs.launchpad.net/ubuntu/+source/lightdm/+bugs?field.searchtext=lock

[Launchpad Janitor (janitor)]

[Expired for gnome-shell (Ubuntu) because there has been no activity for 60 days.]