Okay, this issue has been addressed in the patch below. We will discuss internally, if we’re keeping it this way. Nevertheless, it must work flawlessly now for any kind of configs, even broken ones.
Give it a try patching a file and restarting Webmin afterwards.
Note: Line 1834 doesn’t exist on your system, don’t look for it and don’t be surprised it’s not there.
The simple way to apply the patch, is to run the following command (from SSH console or in-built Webmin command line), for Debian/Ubuntu:
curl https://raw.githubusercontent.com/virtualmin/virtualmin-gpl/1d7306073f1f002e509ec178d41f0db39d5f2eb6/feature-ssl.pl -o /usr/share/webmin/virtual-server/feature-ssl.pl && systemctl stop webmin && systemctl start webmin
… for RHEL (CentOS/Fedora):
curl https://raw.githubusercontent.com/virtualmin/virtualmin-gpl/1d7306073f1f002e509ec178d41f0db39d5f2eb6/feature-ssl.pl -o /usr/libexec/webmin/virtual-server/feature-ssl.pl && systemctl stop webmin && systemctl start webmin