"Reference required" error when referencing NServiceBus assembly from another project

Question

We are trying to write an application that uses the NServiceBus library in a VB.NET environment. We've been stymied by errors similar to the following:

Reference required to assembly 'NServiceBus, Version=2.0.0.1071, Culture=neutral, PublicKeyToken=9fc386479f8a226c' containing the implemented interface 'NServiceBus.IMessageHandler`1'. Add one to your project.

Our project already includes references to NServiceBus.dll and NServiceBus.Core.dll from the same NServiceBus 2.0 RC2 distribution.

Steps to reproduce:

Create a new VB Class Library Project (.NET 3.5)
Add NServiceBus.dll and NServiceBus.Core.dll as References.

Put the following code in Class1.vb:

Imports NServiceBus.Sagas.Impl
Class Test
    Public Function Foo() As SagaMessageHandler
        Return Nothing
    End Function
End Class

You should now see the compiler error mentioned above.

An identical project written in C# has no compile errors.

Any ideas about how to solve this problem? (And, yes, my preferred solution is switching to C#, but no, that's not an acceptable one at the moment.)

Very weird, was able to reproduce here, too. Can you pull down the source and rebuild it locally? — Chris Haas
Yeah, pulled down the trunk source and built it locally using the provided build script. Had the same problems. Haven't yet looked closely at the build script to see if it might be doing anything that might cause this. — cwegrzyn

cwegrzyn cwegrzyn · Accepted Answer · 2010-02-03T19:52:00

On a hunch that it was an ILMerge-related issue, I found this post suggesting that assembly signing might be responsible.

I downloaded the NServiceBus trunk source, opened up src/core/NServiceBus.sln, and set each of the projects in the solution to sign the assembly with NServiceBus.snk from the source tree root. The new DLLS produced after rebuilding NServiceBus fixed the compiler errors from my original post.

"Reference required" error when referencing NServiceBus assembly from another project

2 Answers