Unable to secure Plesk with a Let's Encrypt certificate. The following error is shown in Plesk:
PLESK_ERROR: Error: Could not issue a Let's Encrypt SSL/TLS certificate for server.example.com.
Authorization for the domain failed.
Invalid response from https://acme-v01.api.letsencrypt.org/acme/authz/JwiJ1oPnjy-8ahXSzgbObDNjn9CrcIjzs87_H_7wEz8.
Detail: Invalid response from http://server.example.com/.well-known/acme-challenge/BjH29Kw9Ttp5bV1QV2kCFpAsGWEfONGUu4iY3bR_GqM
The hostname is resolvable from the Internet:
# nslookup server.example.com 188.8.131.52
The URL http://server.example.com shows a default Plesk page.
The option Default site is set to a hosted website at Tools & Settings > IP addresses > 203.0.113.2 (where 203.0.113.2 is the main Plesk IP address).
In order to secure Plesk with a Let's Encrypt certificate, Plesk IP address should not be attached to a domain.
In Plesk go to Tools & Settings > IP Addresses > 203.0.113.2 (where 203.0.113.2 is the main Plesk IP address)
Set Default site to none.
Click OK to apply the changes.
Secure Plesk with a Let's Encrypt certificate.