Copied SSL certificate 'to webmin' now can't access virtualmin/webmin ERR_SSL_PROTOCOL_ERROR

From within my domain in Virtualmin > SSL, I used the copy/use certificate for Webmin function, this appeared to work however since this I can now NOT access virtualmin/webmin I get the browser ERR_SSL_PROTOCOL_ERROR.

I’m using a newly issued, let’s encrypt SSL certificate for the domain which I clicked the use certificate for Webmin.

What is wrong/how do I fix?

I have the same issue, never figured it out…

If you want to access webmin again, you have to change in /etc/webmin/miniserv.conf ssl=1 to ssl=0 and restart webmin, for ubuntu for example: sudo systemctl webmin restart