MSBuild 4.0 or Visual Studio 2010 may fail to compile a 32-bit application targeted for .NET Framework 3.5, 3.0 or 2.0 on a x64 machine

This article helps you resolve the problem where MSBuild 4.0 or Microsoft Visual Studio 2010 can't compile a 32-bit application that's targeted for .NET Framework 3.5, 3.0 or 2.0 on x64 machine.

Original product version:   Visual Studio 2010
Original KB number:   2028833


You're building an application targeted for x86 configuration on a x64 machine with Visual Studio 2010. The project contains a resource file referencing a 32-bit assembly. Target Framework selected is 3.5, 3.0 or 2.0.

You may get the following error:

Form1.resx(161,5):error RG0000: Could not load file or assembly "<file_name>" or one of its dependencies. An attempt was made to load a program with an incorrect format. Line 161, position 5.

The diagnostic build-log shows that task GenerateResource fails.


Resgen.exe in <system_drive>:\Program Files (x86)\Microsoft SDKs\Windows\vx.x\bin, which is a part of Windows SDK, is marked as MSIL, so it will run as a 64-bit process. It will try to load a 32-bit assembly and fail.


In order to work around this issue, you need to perform the following steps:

  1. Close all instances of Visual Studio.

  2. From the Visual Studio Tools sub folder, open an elevated Visual Studio Command Prompt (2010) (using Run as administrator option). Change directory to <system_drive>:\Program Files (x86)\Microsoft SDKs\Windows\v<x.xx>\bin\.

  3. Issue the command:

    corflags /32bit+ ResGen.exe /force
  4. Open <project_name>.csproj in notepad.

  5. Add the property <ResGenToolArchitecture>Managed32Bit</ResGenToolArchitecture> under the PropertyGroup section. Save and close the csproj file.

More information

If you want to build a .resx file that references a 64-bit assembly targeting v3.5, v3.0 or v2.0, you may have to reverse this workaround before doing so.

CorFlagsCorFlags.exe (CorFlags Conversion Tool) may help you.