When invoking .NET CLR from within C++, an error is returned

I am calling a .NET assembly from C++.

This works perfectly for any test .NET 4.0 projects that I call.

However, when calling a large project with 20 sub-assemblies, it fails with the error below:

Failed to execute assembly: 0x80004003. GetLastError=126. dwReturn=1.

Here is the C++ code that generates the error:

DWORD dwReturn;
hr = pCLR->ExecuteInDefaultAppDomain(szApplication, szEntryType, szEntryMethod, szParameter, &dwReturn);
if (FAILED(hr))
{
    // Fails if I try the production assembly, with 20 subassemblies.
    printf("    Failed to execute assembly: 0x%X. GetLastError=%d. dwReturn=%d.\n", hr, GetLastError(), dwReturn);
}
else
{
    // Works 100% if I plug in a small toy assembly in .NET 4.0.
    wprintf(L"    Assembly returned: %d\n", dwReturn);
}

Environment

• Visual Studio 2010 SP1.
• C++ for the code above.
• .NET 4.0 for the target assembly.

Your managed code died with a NullReferenceException. Its Exception.HResult value is 0x80004003, E_POINTER.

Clearly that's a very common reason for managed code to die. In the transition from managed code back to native code, you'll lose a lot of context for the exception. That puts a burden on the managed code to do some essential error logging, at least the all-mighty Exception.StackTrace. The .NET 4 AppDomain.FirstChanceException event can be useful.

Debug the problem by enabling managed code debugging, Project + Properties, Debugging, Debugger Type = Mixed. And Debug + Exceptions, Thrown checkbox for CLR exceptions so the debugger stops the program when the exception is thrown.