The vSphere Web Client may display the following error:

Failed to verify the SSL certificate for one or more vCenter Server Systems: https://vCenter-Server-FQDN:443/sdk

or

Could not connect to one or more vCenter Server Systems:https://vCenterFQDN:443/sdk

Additionally, objects such as hosts or VMs are not displayed in the vSphere Web Client.

These errors usually occur with a re-installation or upgrade of vCenter Server, where the vCenter Server is registered to the same vSphere SSO more than once.

The faulty registration needs to be resolved by unregistered all duplicate vCenter Server instances from vSphere SSO, so only the correct registrations remain.

You will have to unregister al  ...