A virtual machine’s virtual hardware version defines the constraints around which physical resources can be presented and consumed by a VM. This value is expressed in a number of different ways: the virtual hardware version, the VM Version, a “vmx-#” value, or the compatibility version.
For example, hardware version 10 VMs often show up as being compatible with “ESXi 5.5 and later (VM version 10)” in the vSphere Web Client’s summary tab. I’ve provided a sample screenshot below.
You can’t easily work with VMs that are using this version unless you have access to the Web Client. If you ever find yourself in a situation where the Web Client is offline or so slow, you’re reduced to the legacy vSphere C# Client (the Windows vSphere Client that has been used for years, sometimes called the Thick Client). The vSphere Client cannot edit VMs using Hardware Version 10.
Now move to the VMware website and search for the VMware vSphere Client 5.5 Update 2. Specifically VMware-viclient-all-5.5.0-1993072.exe (build 1993072).
This means that all infrastructure VMs that power your vSphere management should never been upgraded beyond Hardware Version 9. Until now. The vSphere Client bundled with ESXi 5.5 Update 2 is able to edit Hardware Version 10 VMs. You don’t even have to upgrade your hosts to ESXi 5.5 Update 2; you only need the updated vSphere Client. After upgrading your VIclient when you try to edit that Hardware Version 10 machine, a different popup appears.
The vSphere Client is now exposing all Hardware Version 8 and below features, which is plenty to do some minor troubleshooting such as changing the network adapter, editing the vCPUs and memory, or edit a virtual hard drive.
Here is the screenshot which is showing its HW version and you can edit it via default vi Client.