You have probably been greeted with the following error while trying to generate an SSL certificate with LetsEncrypt and thats why you are looking at this article:
[root@server conf.d]# certbot --apache
Saving debug log to /var/log/letsencrypt/letsencrypt.log
Error while running apachectl configtest.
AH00526: Syntax error on line 85 of /etc/httpd/conf.d/ssl.conf:
SSLCertificateFile: file '/etc/pki/tls/certs/localhost.crt' does not exist or is empty
The good news is that this is normally nothing to worry about. The easiest way to cure the issue is to run the following command:
/usr/libexec/httpd-ssl-gencerts
Then restarting httpd with the following:
systemctl restart httpd
The issue should not return after the series of commands are completed.