Type library exporter encountered a type that derives from a generic class and is not marked as ClassInterface(ClassInterfaceType.None)]. ...

Type library exporter encountered a type that derives from a generic class and is not marked as [ClassInterface(ClassInterfaceType.None)]. Class interfaces cannot be exposed for such types. Consider marking the type with [ClassInterface(ClassInterfaceType.None)] and exposing an explicit interface as the default interface to COM using the ComDefaultInterface attribute.