Unable to access Plesk with the following error in Firefox:
CONFIG_TEXT: The owner of server.example.com has configured their website improperly. To protect your information from being stolen, Firefox has not connected to this website.
This site uses HTTP Strict Transport Security (HSTS) to specify that Firefox may only connect to it securely. As a result, it is not possible to add an exception for this certificate.
server.example.com uses an invalid security certificate. The certificate expired on September 06 2017 The current time is October 05 2017 Error code: SEC_ERROR_EXPIRED_CERTIFICATE
CONFIG_TEXT: Your connection is not private
Attackers might be trying to steal your information from server.example.com (for example, passwords, messages, or credit cards). Learn more
Browser console detects that the SSL used for securing Plesk page server.example.com is valid for *.example.com domain and expired in the past.
But active SSL is shown for example.com domain that expires in future
Expired SSL is chosen for securing Plesk in Tools and Settings > SSL/TLS Certificates
Check what SSL is used for securing example.com: Domains > example.com > Hosting Settings
Select the same SSL for securing Plesk in Tools and Settings > SSL/TLS Certificates