This weekend I decided to take advantage of the Windows Phone Preview Program for Developers and update my Lumia 920 to Update 3 for WP8. While Update 3 was downloading and installing on my phone, I decided to install the Windows Phone SDK 8.0 which includes Visual Studio Express for Windows Phone on a Win 8.1 VM that I use for development purposes.

Installation was quick and painless until the very end when I received a message stating that the installation was unable to enable Hyper-V. When I tried to enable it manually by going into Control Panel -> Programs & Features -> Turn Windows Features On or Off, the Hyper-V Platform checkbox was grayed out. Upon hovering over the check box I received a tool tip stating “Hyper-V cannot be installed: A Hypervisor is Already Running”.

At this point I was confused as I had previously installed VS Express for Windows Phone on another VM and had successfully run it along with the emulator (the emulator runs in Hyper-V). Because of this I knew the VM host machine was correctly setup to allow VM Workstation to run virtualized environments within VM’s. I then compared the two VM’s and found there were a few differences:

  • Original install was an older version of VS Express for Windows Phone
  • Original install was on a Windows 8 VM
  • New install was the latest version of VS Express for Windows Phone
  • New install was on a Windows 8.1 VM
  • Both VM’s are running on VM Workstation 9.0.1

After reviewing the two VM’s I realized there must be something different with either the latest version of VS Express for Windows Phone, Windows 8.1, or both. Doing a little more research I found there were two things I needed to do:

  1. Enable “Virtualize Intel VT-x/EPT or AMD-V/RVI” in the settings of the VM

  2. Open the .vmx file for the virtual machine in a text editor and add the following lines to the end of it

    1. hypervisor.cpuid.v0 = “FALSE”
    2. mce.enable = “TRUE”

After doing both of these I started the VM and intended to go back in and turn on Hyper-V, however, when I got back to the settings I was happy to see that “Hyper-V Platform” was already enabled.


With Hyper-V successfully enabled and running I was then able to run VS Express for Windows Phone along with the Windows Phone Emulator.

By the time I was finished with this, Update 3 had successfully installed on my phone and I was ready to go. Now, not only do I not have to wait for AT&T to release updates, but I can start developing apps for my phone as well. Now I just need to find the spare time and start developing!