If you add an ESX 3.5 host to your vSphere Cluster,there is a change you’ll get this warning:


The solution is simple, you need the “old” license server running in your network. So download the “old” license server from


Install the License Server for ESX 3.5 on different server than your vCenter box. I tried installing it on the same box, but it ended with a failed startup of the License server services. The installation is straight forward (read next, next, add license file, next and finish).

After the installation open the vCenter Service Settings option.


And enter the address of your license server and press ok.


Now it’s possible to add the ESX 3.5 host to your cluster.


7 thoughts on “Add an ESX 3.x host to your vSphere Cluster

  1. Hi Arne,

    Did this setup actually work? In a ESX 3.5 / vCenter 2.5 U4 environment I once set up a license server on a different machine than the vCenter server. ESX started complaining that the servername of the license server and vCenter server were different and I was unable to start any VM’s on that ESX host.



  2. Too bad the 3.5 license server does not install on Windows 2008 R2 64bit (I got an error about rights at install time).

    This makes migrating to vSphere vCenter on 64-bit and new OS a bit harder.

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