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There are two .dll files, one written in C++ (providing an API via P/Invoke), and the other in C# (.NET 4.5.2), which exports it. There was a need to rewrite everything in C++/CLI. Everything was done, and if you run the resulting output through a test utility in the build output folder, it works perfectly. However, when copying to the server (also written in C#, .NET 4.8), an exception System.IO.FileNotFoundException: Could not load file or assembly referencing a CLR DLL occurs. This happens at the moment of binding C# delegates and static methods of the new CLR class in the C++ library (I tried doing it without delegates - the result is the same. I also tried creating a full class object and referencing its method in the delegate - the same result). Moreover, if you combine the old P/Invoke and the new CLR, the exception only occurs when accessing the new API, while P/Invoke calls link normally. Both libraries are in the same path on the server, in the same folder. In the reference settings for the C# library, I specified the path to the C++/CLI DLL in the build output directory - to no avail.
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Hi @Eugene Traty ,Welcome to Microsoft Q&A,
Your C# DLL is .NET 4.5.2, but the server is running .NET 4.8. While .NET 4.8 should be compatible with 4.5.2, this can cause problems if your C++/CLI DLL depends on certain assemblies that are specific to that .NET version. Since you're only exporting C++, have you tried changing to the same version? Does the C++/CLI target platform (x86/x64) match the server?
You can look at my Dependency Walker output for C++/CLI .dll behind. There is no dependency with MSCOREE.DLL for C# dll which exports C++/CLI and this is the only one dependency for it. The using platform is x64 and it's the same for server and dll builds both
By the way , if i repeat all these actions for P/Invoke approach - it works properly
Although P/Invoke can directly call native DLL, C++/CLI is a managed assembly and must comply with .NET assembly loading rules. If it is not troublesome, it is recommended that you do not mix versions. Also check whether your server has VC++ runtime installed.
First try to manually load C++/CLI DLL Add in C# code:
AppDomain.CurrentDomain.AssemblyResolve += (sender, args) =>
{
string dllPath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "YourCppCli.dll");
return File.Exists(dllPath) ? Assembly.LoadFrom(dllPath) : null;
};
Here is my C++ project configs in case Debug mode
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The DLL should be distributed in release mode when deploying to different machines. Have you tried to build the dll project on your Server?