Error starting vncsever-enterprise

When I try starting vncserver enterprise, I get

openstack@tjcw-vdc-sdn-4:~$ vncserver-virtual :4
VNC(R) Server 6.8.0 (r45849) x64 (Oct 14 2021 14:50:18)
Copyright (C) RealVNC Ltd.
RealVNC and VNC are trademarks of RealVNC Ltd and are protected by trademark
registrations and/or pending trademark applications in the European Union,
United States of America and other jurisdictions.
Protected by UK patent 2481870; US patent 8760366; EU patent 2652951.
See https://www.realvnc.com for information on VNC.
For third party acknowledgements see:
https://www.realvnc.com/docs/6/foss.html
OS: Ubuntu 20.04, Linux 5.4.0, amd64

Bad argv0
Error: Error querying VNC settings.
openstack@tjcw-vdc-sdn-4:~$ 

What does the error message mean, and what should I do to fix the problem ?