This is a rather simple one, but it took me an hour to finally realize what was going on.
I got this error when trying to execute a custom method on my AM from a backing bean.
To execute the method, I got the OperationBinding from the binding container and called execute on it.
When testing I got this error.
The error ,message basically explains that the method could not be found or is not supported. That should have been a good indicator, but I "knew" the method existed. What happened was that I had created the binding first, then changed the method signature on the AM and the client interface, but forgot to re-create the binding. So the parameters(in my case) that the binding had no longer was available on the AM's client interface.
Another thing to note here is the use of generics.