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