Why the following message is thrown while accessing Plesk?
Your connection is not private
This Connection is Untrusted
(Error code: sec_error_unknown_issuer)
In Internet Explorer:
There is a problem with this website’s security certificate.
By default, Plesk is using self-signed certificate that does not have a signature from trust center.
After adding the IP address/hostname/domain to exception for web browser, message will not be shown again for this IP address/hostname/domain.
To use Plesk over HTTPS protocol without this message a valid SSL certificate signed for IP address/hostname/domain by trust center is required. See Administrator's Guide - Getting SSL Certificates for details.
To add a purchased SSL certificate to Plesk, follow this path:
Plesk > Tools & Settings > SSL Certificates > Secure Plesk
Also, Plesk can be accessed via HTTP protocol, for example: