I'm using Windows 10 Insider Preview build 10074 which was updated from Windows 8.1. I installed Visual Studio Enterprise 2015 RC. I also installed Windows 10 SDK and phone emulators. When I try to launch an app on an emulator, an error message is displayed saying "The windows phone emulator wasn't able to set some properties on the virtual machine." The error is related to changing resolution on Virtual Machine. This happens on both of my laptops that I tried on.
Searching on web points to enabling Hyper-V but it is already enabled and working fine.
How can I fix this?
This happens when you upgrade your windows and hyper-v virtual machine's configurations are not updated alongside.
Open Hyper-V Manager app (in windows 10) > choose your machine that's giving erros > on the right, click 'upgrade configuration' and choose 'upgrade'.
That should update your Virtual Machine configuration for that windows 10 phone emulator and the emulator should work fine.
This problem occurred on both of my laptops and doing this fixed it.