My domain is: leaf.arpnic.net
I ran this command: sudo certbot renew --cert-name leaf.arpnic.net
It produced this output:
Saving debug log to /var/log/letsencrypt/letsencrypt.log
Processing /etc/letsencrypt/renewal/leaf.arpnic.net.conf
Renewing an existing certificate for leaf.arpnic.net
Failed to renew certificate leaf.arpnic.net with error: Could not bind TCP port 80 because it is already in use by another process on this system (such as a web server). Please stop the program in question and then try again.
All renewals failed. The following certificates could not be renewed:
/etc/letsencrypt/live/leaf.arpnic.net/fullchain.pem (failure)
1 renew failure(s), 0 parse failure(s)
Ask for help or search for solutions at https://community.letsencrypt.org. See the logfile /var/log/letsencrypt/letsencrypt.log or re-run Certbot with -v for more details.
My web server is (include version): This is used by postfix, not a web server
The operating system my web server runs on is (include version): RHEL 8.10
My hosting provider, if applicable, is:
I can login to a root shell on my machine (yes or no, or I don't know): yes
I'm using a control panel to manage my site (no, or provide the name and version of the control panel): no
The version of my client is (e.g. output of certbot --version or certbot-auto --version if you're using Certbot): certbot 5.0.0