Update for UbuntuMATE 16.04.6 broke the GUI

Tue Aug 27 20:40:08 UTC 2019

On Wed, 28 Aug 2019 02:10:00 +0800, Bret Busby wrote:
>dconf-WARNING **: failed to commit changes to dconf: Cannot autolaunch
>D-Bus without X11 $DISPLAY

Start a X session for your new user and then use gsettings to edit
dconf for the old user.

sudo -Hu olduser dbus-launch gsettings [...]

https://askubuntu.com/questions/1134453/how-to-run-gsettings-for-another-user-ubuntu-18-04-2-lts