Fix “Hyper-V cannot be installed: A hypervisor is already running” message in Fusion and Workstation

As you know, recent versions of VMware Workstation and VMware Fusion include the ability to run hypervisor-based applications inside a virtual machine running on those platforms.  However, even if you’ve configured your virtual machine to enable this support (using the instructions found in this article: VMware Fusion 5: Enable VT-x/EPT inside a virtual machine), when you attempt to install the Hyper-V component on Windows 8, you receive the error message “Hyper-V cannot be installed: A hypervisor is already running.”

This is easily correctable

  1. First, shut down the Windows 8 virtual machine.
  2. Make certain that you’ve enabled VT-x/EPT in your virtual machine (VMware Fusion 5: Enable VT-x/EPT inside a virtual machine)
  3. Modify the vmx file associated with your Windows 8 virtual machine.  For my virtual machine, the vmx file is located at /Users/slowe/Documents/Virtual Machines.localized/Windows 8.vmwarevm/Windows 8.vmx.
  4. Add the following lines to the end of the VMX file:
    1. hypervisor.cpuid.v0 = “FALSE”
    2. mce.enable = “TRUE”
  5. Restart your virtual machine.

7 thoughts on “Fix “Hyper-V cannot be installed: A hypervisor is already running” message in Fusion and Workstation”

  1. Hi, im using a Fusion 6 trial version and a windows 8.1 trial version. I have the same problem but i didnt find the vmx file in this or any localization on my mac or windows.

  2. Thnx.Vey much It's perfectly works for Windows 2012 R2 STD on Wokstation 11
    Thes was tird me for now i,m hepy thanke you

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