I had the same issue with a new install; letsencrypt wouldn't let me install a certificate for plesk itself. turned out the ownership for "/opt/psa/var/certificates/" was set to root. Setting the permissions to psaadm solved my issue (chown psaadm:psaadm /opt/psa/var/certificates/*).
It did...
I had the same issue with a new install; letsencrypt wouldn't let me install a certificate for plesk itself. turned out the ownership for "/opt/psa/var/certificates/" was set to root. Setting the permissions to psaadm solved my issue (chown psaadm:psaadm /opt/psa/var/certificates/*).
It did...