Had the same – unter x2go, pop up window:

Could not acquire name on session bus

System : zesty

Desktop: ubuntu-mate

edit the file:  

/etc/systemd/system/display-manager.service

right under section [Service]

add:

unset SESSION_MANAGER

unset DBUS_SESSION_BUS_ADDRESS

And reboot the machine. Then it is working again.

Yours sincerely

Rnowotny / Vienna