When you prepare an ESXi 5.x host, vCloud Director installs agent software on the host. The agent software is not installed on ESXi 6.x and later. After you upgrade an ESXi 5.x host to a later 5.x release, you must upgrade its host agent.
The host must be running an ESXi 5.x release. If the host is running 6.x or later, the Upgrade Host option is unavailable.
- Click the Manage & Monitor tab and click Hosts in the left pane.
- Right-click the host name and select Upgrade Host.