Invalid PID file

I was in Virtualmin/Webmin on a virtual server that is the default server which has an SSL cert on it. Thats been working fine for long time now. I clicked the button to copy the certs to Webmin it then showed me error page.

I SSH’d in and ran virtualmin check-config

The last line (twice) showed:
Invalid PID file /var/webmin/

I deleted this file thinking that it would be recreated again when Webmin was restarted. but no.

How can I get access again?