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! -- You received this bug notification because you are a member of Ubuntu Desktop Bugs, which is subscribed to gnome-shell in Ubuntu. https://bugs.launchpad.net/bugs/1715435 Title: Can't lock screen when using lightdm with gnome-shell To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/gnome-shell/+bug/1715435/+subscriptions -- desktop-bugs mailing list desktop-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/desktop-bugs