Created attachment 4578 [details]
App that shows the bug
If KnownType("methodName") is defined in base class, the method in ms.net is searched in type hierarchy. On Mono it is not, and serialization throws InvalidDataContractException.
Check the attached app. Compile it with: mcs Program.cs
This is my fix:
Just ran into this issue.
What's happening with this? Why hasn't the fix been merged?