TigerVNC Server setup fails

Thank-you, I found it these days. In your how-to you write

$SESSION according to your installation e.g. openbox)
Is this freely configurable like a variable’s name?

I am running into the error message:

Failed to start vncserver@:2.service: Unit vncserver@:2.service has a bad unit file setting.
See system logs and ‘systemctl status vncserver@:2.service’ for details.

systemctl status vncserver@:2.service
Aug 16 12:27:34 ManjaroServer systemd[1]: vncserver@:2.service: Unit configuration has fatal error, unit will not be started.

Any comments?