runtime: BadImageFormatException when loading C++/CLI DLLs in Core 3.1

Operating System Version: Azure virtual machine with a Windows 10 Pro, Version 1809 base .NET Core Version: 3.1 Visual Studio Version: 16.4.3 and 16.4.4

Whenever I attempt to access a C++/CLI project (targeted for .NET Core 3.1) from a C# project, the execution will immediately crash when attempting to load the assembly.

I have managed to reproduce this error in multiple independent solutions, on multiple computers, so it does not appear to be tied to a code- or computer-specific issue on my end.

If the project is executed in Visual Studio with the debugger, the debugger itself appears crash upon reaching the method which calls the C++/CLI DLL. No information will be provided in Debug other than these lines:

The program ‘[13640] NET Core CLI Test.exe: Program Trace’ has exited with code 0 (0x0). The program ‘[13640] NET Core CLI Test.exe’ has exited with code -529697949 (0xe06d7363) ‘Microsoft C++ Exception’.

As a curious note, the debugger also skips over the calling method if I attempt to step into it, reporting it as “non-user code”.

If executed without a debugger, more information is provided when the crash occurs:

Unhandled exception. System.BadImageFormatException: Could not load file or assembly ‘Mock CLI Project, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null’. An attempt was made to load a program with an incorrect format. File name: ‘Mock CLI Project, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null’ at NET_Core_CLI_Test.Program.CallingMethod(Int32 a, Int32 b) at NET_Core_CLI_Test.Program.Main(String[] args) in C:\Users\travis.ridge\source\repos\NET Core CLI Test\NET Core CLI Test\Program.cs:line 11

In both situations, an error will be added to the Windows event log, displaying the same basic information each time.

Faulting application name: NET Core CLI Test.exe, version: 1.0.0.0, time stamp: 0x5dedc13b Faulting module name: KERNELBASE.dll, version: 10.0.17763.914, time stamp: 0xfb6790ac Exception code: 0xe0434352 Fault offset: 0x0000000000039159 Faulting process id: 0x31e0 Faulting application start time: 0x01d5d8549d80476e Faulting application path: C:\Users\travis.ridge\source\repos\NET Core CLI Test\NET Core CLI Test\bin\x64\Debug\netcoreapp3.1\NET Core CLI Test.exe Faulting module path: C:\windows\System32\KERNELBASE.dll Report Id: 575a2b9a-1f69-4d48-8d07-ac8dfe6917d4 Faulting package full name: Faulting package-relative application ID:

Below I’ve included the code example from a minimal solution in Visual Studio with which I am able to consistently reproduce this issue.

Example C# script. The program crashes when CallingMethod() is invoked.

using CLI;

namespace NET_Core_CLI_Test
{
    class Program
    {
        static void Main(string[] args)
        {
            int a = 2;
            int b = 2;
            int sum = CallingMethod(a, b); //Crash occurs when executing this line
        }

        static int CallingMethod(int a, int b)
        {
            //Execution never reaches here
            MockWrapper wrapper = new MockWrapper();
            return wrapper.Add(a, b);
        }
    }
}

The ModelWrapper.cpp class:

#pragma once
#include "pch.h"
#include "MockWrapper.h"

#include <exception>

using namespace System;
using namespace System::Runtime::InteropServices;

namespace CLI {
	MockWrapper::MockWrapper() {

	}

	int MockWrapper::Add(int a, int b) {
		return a + b;
	}
}

I can provide further information upon request.