Ubuntu
lightdm package

  1. Bug #1715435
  2. Comment #14

Comment 14 for bug 1715435

Revision history for this message
Dmytro Korzhevin (korg) wrote : Re: Can't lock screen with keyboard shortcuts when using lightdm

> 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)