Windows 10 Mobile Emulator fails to start with 0x800705AA error

I recently moved to a new machine and while attempting to debug a UWP app in the Windows 10 Mobile emulator, I came across the following error message:

0x800705AA error message

I couldn’t find any information on this 0x800705AA error, but I eventually tracked this to be caused by the fact Hyper-V was using the machine GPU with RemoteFX!

The easiest way to fix this I found was to just disable RemoteFX; to do so, follow these steps:

  • open Hyper-V Manager (just press Win+R, type virtmgmt.msc and hit Enter)
  • on the left pane, right-click the machine name and then click “Hyper-V Settings”
  • on the tree, select “Physical GPUs”
  • untick “Use this GPU with RemoteFX” and click OK

Hyper-V Settings updated

After disabling RemoveFX, remove any Windows 10 Mobile emulator from the “Virtual Machines” list (Visual Studio will re-create these) and just deploy from Visual Studio again and you should now be able to launch the emulator!