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Knowledge Base

Not possible to connect server to Plesk 360: The server has an invalid certificate

 
360httpsipplatform 360plesk 360

Symptoms

  • Unable to add a server to Plesk 360 with one of the errors below:

    The server has an invalid certificate


    Hostname/IP does not match certificate's altnames


    A self-signed certificate is installed


    The certificate has expired

  • The hostname without a valid certificate or the IP address (i.e. https://213.0.1.2:8443) is used to connect the server to Plesk 360

Cause

Plesk URL used to connect the server is not secured by a valid certificate.

Resolution

  1. Check if any related hostname is secured with an existing certificate under Tools & Settings > SSL/TLS certificates > Certificate for securing Plesk.

    Note: That might be verified by using external resources as well - such as Qualsys SSL Labs, SSL Shopper.

    If the certificate is presented and valid, use the related hostname:

    • specify https://server.hostname.com:8443 on adding the server to Plesk 360
    • access the Plesk UI via https://server.hostname.com:8443 and add the server to Plesk 360 from there
  2. If there is no valid certificate, use the below article to secure Plesk URL:
    How to secure a Plesk hostname on port 8443 with an SSL certificate (Let's Encrypt / other certificate authorities)
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