Perform a vCenter Server upgrade as part of the same maintenance window during which you upgrade other VMware Horizon server components. Before you upgrade vCenter Server, you must back up some VMware Horizon data.

Note: During the vCenter Server upgrade, existing remote desktop and application sessions will not be disconnected, but the following functionality is not available during the vCenter Server upgrade:
  • Remote desktops that are in a provisioning state will not get powered on.
  • New desktops cannot be launched.


  • Determine when to perform this procedure. Choose an available desktop maintenance window. For information about how much time is required, see the VMware vSphere Upgrade Guide.
  • Back up the vCenter Server database.
  • Back up the Horizon Directory database from a Connection Server instance by using the vdmexport.exe utility.

    For instructions, see the Horizon Administration document. If you have multiple instances of Connection Server in a replicated group, you need to export the data from only one instance.

  • Verify that the server on which vCenter Server is installed has a CA (certificate authority)-signed TLS server certificate installed and configured. After you upgrade Connection Server, if vCenter Server does not use a CA-signed certificate, the default self-signed certificate is shown as invalid in Horizon Console, and a message indicates that vCenter Server is unavailable.
  • Complete the prerequisites listed in the VMware vSphere Upgrade Guide, using the version of the guide that corresponds to the version of vSphere that you plan to upgrade to.
  • To upgrade vCenter Server while instant clones are in use, see the steps in the VMware Knowledge Base (KB) article


  1. Upgrade vCenter Server as described in the VMware vSphere Upgrade Guide.
    Important: If your clusters contain vSAN datastores, also see the chapter about upgrading the vSAN cluster, in the Administering VMware vSAN document. This chapter contains a topic about upgrading vCenter Server.
  2. Log in to Horizon Console and examine the dashboard to verify that the vCenter Server icon is green.
    If this icon is red and an Invalid Certificate Detected dialog box appears, you must click Verify and either accept the thumbprint of the untrusted certificate, as described in "What to Do Next," or install a valid CA-signed SSL certificate.

    For information about replacing the default certificate for vCenter Server, see the VMware vSphere Examples and Scenarios document.

What to do next

To use a default or self-signed certificate from vCenter Server, see Accept the Thumbprint of a Default TLS Certificate.

If you have finished upgrading VMware Horizon server components, at your next maintenance window, continue with the VMware Horizon upgrade.