Error building project when referencing native assembly dependency in app.manifest

If you're using an app.manifest, and defining assembly dependencies (i.e. for SxS / Side by side / Reg-free COM etc), you may encounter this error when you build the project:

Could not find file 'AssemblyName, Version=x.x.x.x, PublicKeyToken=xxxxxxxxxxx, ProcessorArchitecture=x86, Type=win32'.

This is even when the native assembly is in place where the project can find it.

Example

Your app.manifest may contain this fragment:

 <dependency>
    <dependentAssembly>
        <assemblyIdentity name="Native.Custom" version="1.0.0.0" processorArchitecture="x86" type="win32" publicKeyToken="12345678"/>
    </dependentAssembly>
</dependency>

This manifest is available to the project, with the manifest file in the project directory or in a subdirectory called Native.Custom.

In this case, I have a sub directory called Native.Custom, which contains my Native.Custom.manifest file.

Solution

The problem may be because the ClickOnce manifests are being generated.

1. Open your project file in a text editor (or right click it in Visual Studio and choose Edit Project)
2. Find the GenerateManifests element and set it to false: <GenerateManifests>false</GenerateManifests>
3. Save the project and reload it.

Now you should hopefully be able to build.