How do I fix the Visual Studio compile error, “mis

Question

I'm new to project configuration in Visual Studio 2010, but I've done some research and still can't quite figure this issue out. I have a Visual Studio solution with a C++ DLL referencing the C# DLL. The C# DLL references a few other DLLs, some within my project and some external. When I try to compile the C++ DLL, I get this warning:

warning MSB3270: There was a mismatch between the processor architecture of the project being build "MSIL" and the processor architecture of the reference "[internal C# dll]", "x86".

It tells me to go to Configuration Manager to align my architectures. The C# DLL is set up with platform target x86. If I try to change this to something else, like Any CPU, it complains because one of the external DLLs it depends on has platform target x86.

When I look at Configuration Manager it shows the Platform for my C# DLL as x86 and for my C++ project as Win32. This seems like the right setup; surely I don't want the project for my C++ project to have platform set to x64, which is the only other option presented.

What am I doing wrong here?

Answer 1

For my project, I have a requirement to be able to build to both x86 and x64. The problem with this is that whenever you add references while using one, then it complains when you build the other.

My solution is to manually edit the *.csproj files so that lines like these:

<Reference Include="MyLibrary.MyNamespace, Version=1.0.0.0, Culture=neutral, processorArchitecture=x86"/>

<Reference Include="MyLibrary.MyNamespace, Version=1.0.0.0, Culture=neutral, processorArchitecture=AMD64"/>

<Reference Include="MyLibrary.MyNamespace, Version=1.0.0.0, Culture=neutral, processorArchitecture=MSIL"/>

get changed to this:

<Reference Include="MyLibrary.MyNamespace, Version=1.0.0.0, Culture=neutral"/>

Answer 2

In addition to David Sacks answer, you may also need to go to the Build tab of the Project Properties and set Platform Target to x86 for the project that is giving you these warnings. Though you might expect it to be, this setting does not seem to be perfectly synchronized with the setting in the configuration manager.

Answer 3

This warning seems to have been introduced with the new Visual Studio 11 Beta and .NET 4.5, although I suppose it might have been possible before.

First, it really is just a warning. It should not hurt anything if you are just dealing with x86 dependencies. Microsoft is just trying to warn you when you state that your project is compatible with "Any CPU" but you have a dependency on a project or .dll assembly that is either x86 or x64. Because you have an x86 dependency, technically your project is therefore not "Any CPU" compatible. To make the warning go away, you should actually change your project from "Any CPU" to "x86". This is very easy to do, here are the steps.

1. Go to the Build|Configuration Manager menu item.
2. Find your project in the list, under Platform it will say "Any CPU"
3. Select the "Any CPU" option from the drop down and then select <New..>
4. From that dialog, select x86 from the "New Platform" drop down and make sure "Any CPU" is selected in the "Copy settings from" drop down.
5. Hit OK
6. You will want to select x86 for both the Debug and Release configurations.

This will make the warning go away and also state that your assembly or project is now no longer "Any CPU" compatible but now x86 specific. This is also applicable if you are building a 64 bit project that has an x64 dependency; you would just select x64 instead.

One other note, projects can be "Any CPU" compatible usually if they are pure .NET projects. This issue only comes up if you introduce a dependency (3rd party dll or your own C++ managed project) that targets a specific processor architecture.

Answer 4

The C# DLL is set up with platform target x86

Which is kind of the problem, a DLL doesn't actually get to choose what the bitness of the process will be. That's entirely determined by the EXE project, that's the first assembly that gets loaded so its Platform target setting is the one that counts and sets the bitness for the process.

The DLLs have no choice, they need to be compatible with the process bitness. If they are not then you'll get a big Kaboom with a BadImageFormatException when your code tries to use them.

So a good selection for the DLLs is AnyCPU so they work either way. That makes lots of sense for C# DLLs, they do work either way. But sure, not your C++/CLI mixed mode DLL, it contains unmanaged code that can only work well when the process runs in 32-bit mode. You can get the build system to generate warnings about that. Which is exactly what you got. Just warnings, it still builds properly.

Just punt the problem. Set the EXE project's Platform target to x86, it isn't going to work with any other setting. And just keep all the DLL projects at AnyCPU.

Answer 5

There should be a way to make a .NET EXE/DLL AnyCPU, and any unmanaged DLLs it depends on compiled both with x86 and x64, both bundled perhaps with different filenames and then the .NET module dynamically loading the correct one based on its runtime processor architecture. That would make AnyCPU powerful. If the C++ DLL only supports x86 or x64 then AnyCPU is of course pointless. But the bundling both idea I have yet to see implemented as the configuration manager does not even provide a means to build the same project twice with a different configuration/platform for multiple bundling allowing AnyCPU or even other concepts like any configuration to be possible.

Answer 6

I got this warning in Visual Studio 2012 when compiling a SQL Server 2012 SP1 SSIS pipeline script task - until I installed SQL Server 2012 SP2.