Migrating / vMotion virtual machine from ESXi 4.x to 5.0 throws the error: “Virtual machine has 2 virtual CPUs, but the host only supports 1. The number of virtual CPUs may be limited by the guest OS selected for the virtual machine or by the licensing for the host.”

Problem

You’ve just completed the upgrade of 3 out of 4 of your blades from ESXi 4.1 to 5.0 attempt to migrate / vMotion the virtual machines from the ESXi 4.1 blade to the other 3 upgrade ESXi 5.0 blades but receive the following error:

Virtual machine has 2 virtual CPUs, but the host only supports 1. The number of virtual CPUs may be limited by the guest OS selected for the vitual machine or by the licensing for the host.

The value for the virtual CPUs may vary but you are unable to vMotion the virtual machine.

Solution

The reason why you’re encountering this error is similar to the following KB which applies to the older versions of ESX and ESXi: http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1003741

You upgraded ESXi 5.0 hosts were previously licensed under version 4.x and now that it’s upgraded, it’s in a state where it fails the licensing check.  If you navigate into the Manage vSphere Licenses menu, you’ll actually see that your new ESXi 5.0 hosts still references the old vSphere 4 license:

I’m not sure if there’s another workaround because I did not get the option of returning the host to evaluation since the evaluation period has already expired so I just went ahead and upgraded the licenses to version 5, assigned it and go vMotion to start working again.