Combining a C# and C++ project works for x86 and x64 but not for ARM

Question

I have two projects in my solution. One is a C# Universal Application and the other is a C++ project (obtained from here) and re-targetted to Windows 8.1 (this was performed by Visual Studio 15 when I imported the project). I have referenced the C++ project from my C# project and set Copy Local to true.

The code builds perfectly fine for all three platforms (x86, x64 and ARM). However, when deployed to an ARM device there is an exception thrown on the line where I try to access the C++ code. On the x86 and x64 versions this is not an issue and the code works perfectly fine. The exception is a System.IO.FileNotFoundException and here is a pastebin of the exception in detail.

My understanding of this exception is that the generated .dll is for some reason not being copied over onto the device? I have had a look at the configuration settings and everything seems set up correctly as far as I can tell (screenshot incuded below). The other possibility is that the C++ project has an internal dependency on another class that I somehow need to identify and reference from somewhere. There is a line from the stacktrace (included in the above pastebin link) that suggests it occurs on the line System.StubHelpers.StubHelpers.GetWinRTFactoryObject(IntPtr pCPCMD).

The C++ code uses Media Foundation WinRT components and should work perfectly fine on ARM devices.

It seems that other questions on SO (such as here) have also looked at this but only for one particular platform such as x86.

Is there any particular reason why this currently works on x86 and x64 but not on ARM?

Screenshots:

Answer 1

and re-targetted to Windows 8.1

That's your problem right there. If you target a Windows 10 device, you need to create a new Windows Runtime Component (Universal Windows):

My guess is that the Windows 8.1 Winmd is not compatible with the device you selected.

I have downloaded the VideoRecorder tool, and reproduced your problem. Then if I create a new Winmd Universal Windows, add the C++ files in it, it runs without issues on a Raspberry Pi 2 with Windows 10 IoT.

EDIT: If you are targeting a Windows 8.1 device and not a Windows 10 device then you need the Universal Windows 8.1 project:

I've made a sample and deployed it on a Nokia Lumia 925 without issues.