.net - Could not load file or assembly X or one of its dependencies. is not a valid Win32 application. (HRESULT: 0x800700C1)

Question

OS: Windows 8.1 64

I tried to play multiple sounds in VB.Net with DirectX, there are no errors in my code. The problem is whenever the event is fired I get this error

System.BadImageFormatException was unhandled Message: An unhandled exception of type 'System.BadImageFormatException' occurred in System.Windows.Forms.dll Additional information: Could not load file or assembly 'Microsoft.DirectX.AudioVideoPlayback.dll' or one of its dependencies. is not a valid Win32 application. (Exception from HRESULT: 0x800700C1)

Then I set Target CPU to x86 and I got this error

System.IO.FileLoadException was unhandled Message: An unhandled exception of type 'System.IO.FileLoadException' occurred in System.Windows.Forms.dll Additional information: Mixed mode assembly is built against version 'v1.1.4322' of the runtime and cannot be loaded in the 4.0 runtime without additional configuration information.

So far I have tried uninstalling-reinstalling DirectX SDK, Installing everything that has to do with DirectX and different sound files (.wav). Also I had to browse to load the .dlls, I couldn't find them under Reference Manager>Assemblies but now I cant even load them through browse so I use Imports Microsoft.DirectX.AudioVideoPlayback It will let me Import the rest .dlls except(Reference Manager wont even open them):

Microsoft.DirectX.AudioVideoPlayback.dll
Microsoft.DirectX.dll
Microsoft.DirectX.DirectSound.dll

the ones that I need. Is there a way to clean re-install them?

Target Framework: .Net Framework 4.5

CODE:

Dim MySound1 As New Microsoft.DirectX.AudioVideoPlayback.Audio("D:pathsound_file.mp3")

MySound1.Play()

Let me know if you need to know anything else.

UPDATE: I changed the Target Framework to .Net Framework 3.5 and it works fine but only if the CPU Target is set to x86! Why is that?

Answer 1

You are using the olden Managed DirectX wrappers. Targeted to run on .NET 1.1, a framework version that never supported 64-bit code. These wrappers have been deprecated a long time ago, the 2.0 version never made it out of beta.

Changing your EXE's Platform Target to x86 is required, there is no 64-bit version of Managed DirectX and the DLLs contain native 32-bit code written in Managed C++. Furthermore, if you target .NET 4.0 or higher then you have to use a .config file that says that it is okay to load such an ancient assembly that expects native code to run well on .NET 1.1. It should look like this:

<configuration>
  <startup useLegacyV2RuntimeActivationPolicy="true">
    <supportedRuntime version="v4.0"/>
  </startup>
</configuration>

The useLegacyV2RuntimeActivationPolicy attribute suppresses the error message you got. Whether it can actually run on 4.0+ isn't that clear, nobody uses these wrappers anymore. The usual advice is to switch to SharpDX or SlimDX instead.