I'm trying to secure my CentOS 7 VPS with Let's Encrypt. I've followed the guidelines in https://www.digitalocean.com/community/tutorials/how-to-secure-apache-with-let-s-encrypt-on-centos-7 . I've set up virtual hosts, installed server dependencies and the Let's Encrypt client. But when I try to set up the SSL certificate with:
./letsencrypt-auto --apache -d example.com -d mail.example.com
I get the error:
The apache plugin is not working; there may be problems with your existing configuration.
The error was: NoInstallationError()
The Apache Plugin for Let's Encrypt is not working, but how do I make it work?