I'm trying to add VNC server on a VPS, but Gnome won't start
 

Hello,

I've been following this tutorial to install VNC on a Debian VPS:
https://www.digitalocean.com/communi...er-on-debian-8
except I installed Gnome instead of XFCE because I know Gnome better.

The VNC part is working, as I can see a desktop-like window, but all I see is a grey background with this text: "Oh no! Something has gone wrong. A problem has occured and the system can't recover. Please log out and try again."
I couldn't find relevant information about that. Where can I gather more information about the actual problem?

Then, I figured I'd try XFCE anyway, so I installed it but my VNC session always start with Gnome (with the problem described above); how can I tell it to start using XFCE?
I'm afraid to uninstall Gnome now, because, in the tutorial, the XFCE installs with some Gnome dependencies (and my Linux knowledge is not great). It may render both programs unuseable, am I right?