VNC connects, but displays a black screen when trying to launch GNOME

Issue

• When we try to use the VNC viewer connecting to the tigervnc server on this machine, the viewer is getting logged in, but the display is black.

• When VNC is trying to run GNOME, it fails and we get the following messages in the VNC log:

  gnome-session[12345]: WARNING: Could not make bus activated clients aware of DISPLAY=:1 environment variable: Failed to connect to socket /tmp/dbus-xxxxxxxx: Connection refused
  gnome-session[12345]: WARNING: Could not make bus activated clients aware of GNOME_DESKTOP_SESSION_ID=this-is-deprecated environment variable: Failed to connect to socket /tmp/dbus-xxxxxxxx: Connection refused
  gnome-session[12345]: WARNING: Could not make bus activated clients aware of SESSION_MANAGER=local/unix:@/tmp/.ICE-unix/12345,unix/unix:/tmp/.ICE-unix/12345 environment variable: Failed to connect to socket /tmp/dbus-xxxxxxx: Connection refused