Virtual Ethernet card "Virtual Ethernet Adapter" is of type which is not supported

Last week I was asked if I could solve a issue at a customer, they where patching all of their ESXi hosts. Only they ran into a host which refused to go in to maintenance mode, the reason for this was a VM which didn't vMotion to a other host successfully.
Basically, the vMotion task timed-out. When they investigated the error details a more specific error description.

It looked like there was something wrong with the network adapter installed in this specific VM. But when the configuration of this VM was checked it turned out that it had the customers default network adapter installed, VMXNET3.

Having a second look at the VM configuration, the Guest OS was set at Windows 2003 standard for some odd reason. After all this VM was running Windows 2008 R2 Enterprise.

After shutting down the VM and correcting the Guest OS, the VM was powered-on again. Now the VM could be vMotioned without any issue.

Already knowing that it is important to select the proper Guest OS to have VMtools install correctly and to have the right default virtual hardware presented to the VMs OS. There is a extra reason to pay extra attention to choosing the right Guest OS for a VM.

If you want to read more about the impact of a mismatched Guest OS selection, please read this blog post of Frank Denneman.

In this blog post you can also find a PowerCLI "one-liner" by Alan Renouf to quickly scan your environment for mismatched Guest OS.