360 Monitoring detects a website as down while it can be opened in a browser

Symptoms

• 360 Monitoring detects a website as down while it can be opened in a browser

• Under 360 Monitoring > Websites > site_name > Events the error about the SSL certificate is shown:

  [60] SSL peer certificate or SSH remote key was not OK

• SSL Checker confirms that the intermediate certificate is missing and the SSL chain is incomplete

Cause

The website is using a trusted SSL certificate but it is missing a chain/intermediate certificate.

Resolution

Obtain chain/intermediate certificate from a vendor where SSL has been issued and upload it to the domain.

Note: In Plesk, it might be done under Domains > example.com > SSL/TLS Settings > certificate_name > box labeled CA Certificate.

Additional information

The details about the way to complete the certificate chain in Plesk might be found here.