In 18.04, VNC no longer allows multiple logins for same user account



I’ve been using Ubuntu-Mate 14.04 and 16.04 for some time and I’ve been testing out 18.04. One of my workflows requires multiple logins for the same user. Examples: One local GUI login and one VNC desktop session for the same user, or 2 VNC sessions for the same user. In 14.04 and 16.04, this wasn’t a problem, but I can’t make it happen in 18.04. If I have a local GUI login and I attempt to create a VNC desktop session with the following command:

vncserver -geometry 1920x1130 :1

The command works, but after connecting to the session, I see mostly a grey screen with the following error message:

could not acquire name on session bus

The reverse is also a problem, if I have a working VNC session, I can’t log in locally to the GUI. I’ve tried tigervnc and tightvnc, both with the same result. After talking with the tigervnc people, they indicate that some distributions just don’t support more than one GUI login at a time. So, something has changed from 16.04 to 18.04 that now prevents this.

Does anyone know what that might be, or has a work around?