You must prepare the ESXi hosts that are managed by your vCenter Server installation before migrating it from Windows to an appliance.


To migrate vCenter Server or vCenter Single Sign-On from Windows to an appliance, your source and target ESXi hosts must meet the migration requirements.

  • ESXi hosts must be at version 5.5 or greater. If your ESXi hosts are at an earlier version than 5.5, upgrade them to 5.5. Read and follow all best practices when upgrading your hosts to ESXi 5.5.
  • The target ESXi host must not be in lockdown or maintenance mode.


  1. If you have Custom or Thumbprint certificates, see Host Upgrades and Certificates to determine your preparatory steps.
  2. If you have vSphere HA clusters, SSL certificate checking must be enabled.
    If certificate checking is not enabled when you upgrade, vSphere HA fails to configure on the hosts.
    1. Select the vCenter Server instance in the inventory panel.
    2. Select the Manage tab and the General subtab.
    3. Verify that the SSL settings field is set to vCenter Server requires verified host SSL certificates.


Your ESXi hosts are ready for vCenter Server upgrade.