Well, I decided to take the plunge. I installed PHP 7.4 on my Debian 9 to give me until 2022 to deal with either.
The install process of PHP 7.4 was simple/clean. Then the “Re-configure” in Virtualmin went smoothly.
Then, I ran this script suggested by IIia:
#!/bin/sh doms=$(virtualmin list-domains --with-feature web --name-only --no-alias) for dom in $doms; do /usr/sbin/virtualmin disable-feature --domain $dom --web --ssl --logrotate --webalizer /usr/sbin/virtualmin enable-feature --domain $dom --web --ssl --logrotate --webalizer done
And that’s when everything started breaking. About half of my 150 domains got an SSL error and disabled SSL:
Changing IP address of virtual website …
Adding new SSL virtual website …
… certificate file is not valid : Line 31 does not look like PEM format
Saving server details …
Applying web server configuration …
Re-loading Webmin …
Then, when I tried to re-enable SSL, it would fail.
SOLUTION: I had to delete the /home/domain1.com/ssl* files. Then I was able to re-enable the SSL in “Edit Virtual Server -> Enabled features”.