If you have just updated Plesk and server to latest packages, you might find yourself having issues with Let’s Encrypt. If you get following error while installing certificate from Plesk

Could not obtain directory: cURL error 6: Could not resolve host: acme-v01.api.letsencrypt.org 2; Name or service not known (see http://curl.haxx.se/libcurl/c/libcurl-errors.html)

Your openssl has probably been updated as well.

Simply restart of sw-engine and sw-cp-server should do the trick.

systemctl restart sw-engine
systemctl restart sw-cp-server

It’s best to restart php-fpm and nginx as well at this point. But might not be needed.