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Knowledge Base

A warning is shown while accessing Plesk or webmail: The certificate is not trusted or NET::ERR_CERT_AUTHORITY_INVALID

 
domain namedomainsgogooglegoogle chrome

Symptoms

The following error is shown while accessing Plesk or webmail:

  • On Google Chrome:

    Your connection is not private
    NET::ERR_CERT_AUTHORITY_INVALID

  • On Firefox:

    This Connection is Untrusted
    (Error code: sec_error_unknown_issuer)
    Certificate Error: The security certificate presented by this website was issued for a different website's address. This problem might indicate an attempt to fool you or intercept any data you send to the server.

  • On Internet Explorer:

    There is a problem with this website’s security certificate.

  • On Opera

    Opera cannot verify the identity of the server "XXXX", due to a certificate problem. The server could be trying to trick you

Cause

By default, Plesk is using a self-signed certificate that does not have a signature from the trust center.
Or, the mismatched certificate was applied.

Resolution

Note: If Plesk/WebMail is secured via Let's Encrypt, use hostname/domain name to access it because IP address itself cannot be secured with a valid certificate.

In order to avoid the warning, it is required to have a valid SSL certificate. There are several options on how to achieve that:

Secure Plesk/domain/WebMail via Let's Encrypt:

  • For domain/webmail/alias, it is required to go to Websites and Domains > example.com > SSL/TLS Certificates > Install and proceed with the installation. Details are available in the following article:
    How to install SSL certificate for a domain in Plesk
  • For securing Plesk/Mail Server, go to Tools & Settings > SSL/TLS certificates and proceed from there. See the details in the following articles:
    How to secure Plesk login page URL with SSL certificate
    How to secure mail server with Let's Encrypt certificate? 

Use a purchased SSL certificate:

Purchase an SSL certificate signed for IP address/hostname/domain by a trusted center (Certificate Authority) or install Let's Encrypt extension and obtain a free certificate. See Plesk Administration > Securing Plesk > Getting SSL Certificates" href="http://docs.plesk.com/en-US/onyx/administrator-guide/plesk-administration/securing-plesk/getting-ssl-certificates.59466/" target="_blank" rel="noopener"> Administrator's Guide - Getting SSL Certificates for details.

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