Plesk

A website hosted in Plesk is not accessible with HSTS enabled: Potential Security Issue Your connection is not private

Symptoms

A website with HTTP Strict Transport Security (HSTS) enabled at Domains > example.com > SSL/TLS Certificates is not accessible with the following error message:

Cause

The domain has a not-trusted self-signed SSL certificate assigned to secure HTTPS connection. When HTTP Strict Transport Security (HSTS) is enabled and an SSL certificate is invalid, the website will become unavailable.

Another reason is that the website is Disabled.

Resolution

Apply one of the following options: