Created attachment 10090 [details]
Simple VS2012 solution demonstrating the problem
I have a simple WCF service, that communicates with a client over a duplex channel. When the service tries to call back the client it throws an exception when processing the response from the client.
The attached solution demonstrates the problem. You can run it in .NET and it works fine, but when running under mono you will see the server throw an InvalidOperationException after executing the callback. The following error is returned:
Exception DispatchOperation '*' for contract 'ITest' requires Invoker.