C# DLL loaded for exe-application is not found when launching similar DLL by rundll32.exe

Question

I have built a C++/CLI DLL that is a wrapper for some .NET C# DLL. As a sample application I have built a simple project for exe-application based on WindowsForms GUI. It works fine with my C++/CLI library and the mentioned .NET C# DLL. But if I build another C++ DLL, which substitutes this sample exe-application, it doesn't succeed to load the .NET C# DLL, although it is located in the current Windows path. The following exception is occurred when trying to call some function from this C# code:

An unhandled exception of type 'System.IO.FileNotFoundException' occurred in MyApp.dll Additional information: Could not load file or assembly 'xxxx, Version=yyyy, Culture=neutral, PublicKeyToken=null' or one of its dependencies. The system cannot find the file specified

What are possible problems? In general, how should C# DLLs be linked to unmanaged executables? Is it manifest's problem? Thanks in advance.

Answer 1

The windows path is not used when loading .NET Assemblies. The assembly must be in the same folder as the executable, or in the GAC. (That is oversimplified a little, see the link below for more detail)

• Information about the GAC: http://msdn.microsoft.com/en-us/library/yf1d93sz.aspx
• Information about how assemblies are found: http://msdn.microsoft.com/en-us/library/aa720133.aspx