NB: This is not the same issue as in this question (Unable to switch users at lock screen. Unity, Ubuntu 18.04)! In my case lightdm isn't even installed and so reinstalling it is not an option.
I am currently still running Bionic (18.04) with vanilla-gnome-desktop and without Wayland. All of this happens on the console, i.e. not remotely.
When I lock the desktop, there are two options:
- to log back in as the user that it already logged (e.g.
user1) - to log in as another user
The screen shows the full name of the user, a field to enter the password, a button "Cancel", a button "Unlock" and a link of sorts "Log in as another user".
(I have no idea how to make a screenshot at that point, so I don't have one)
As long as I am not already logged on as either user or I am logged on and trying to simply unlock the desktop for the logged on user, this works.
However, when I am already logged on as user1 and now would like to log on as user2 I'm unable to, after clicking the "Log in as another user" link, I will very briefly get a glimpse of the user list and then the screen goes blank. No matter how much I move the mouse or press a key, the only outcome is that after a few seconds I am back to the screen where I need to "slide the screen up" after which I am presented the option to unlock the desktop again (for user1, obviously).
In essence this makes it impossible for me to switch between multiple users, which is odd.
Any insights are appreciated. If there is information missing, let me know in the comments and I'll amend the question.
dpkg -lorapt-cache searchwould have revealed it as well. But thanks anyway. – 0xC0000022L Apr 29 '20 at 09:34