Comment # 2 on bug 1091818 from Freek de Kruijf

(In reply to Neil Rickert from comment #1)
> I'm surprised to see this.
> 
> I ran into this problem a while ago.  But it is no longer happening for me.
> 
> When I first saw the problem, after login to either Plasma-wayland or
> Gnome-wayland, any attempt to login to Plasma-X or Gnome-X would fail
> (return to login screen).  I have not had that happen for a while now. 
> Perhaps it depends on graphics card.  I seem to recall having this problem
> with both SDDM and with GDM.  And I could still login it Icewm.
> 
> The workaround that I used: CTRL-ALT-F1 to get a command line.  Then kill
> any processes running under my userid that were older than the current
> login.  Usually killing the "systemd" process was enough to take down the
> rest.  After that, I could login to X sessions with Plasma and Gnome.

I tried this and indeed I can start a Plasma session, but I consider this still
to be a bug. Closing the Wayland session should end all processes which are
part of that session.