Error="System.Runtime.Serialization.InvalidDataContractException: Type 'System.Collections.ObjectModel.ObservableCollection`1[T]' cannot be exported as a schema type because it is an open generic type. You can only export a generic type if all its generic parameter types are actual types."

Contract=

<ServiceContract()> P

ublic Interface ITestServer
<OperationContract()> <ServiceKnownType(GetType(ObservableCollection(Of )))> _

Function cGetSQLDataSources() As ObservableCollection(Of DarwinObjectModel.DarwinObjectModel.SQLDataSource)

another function in the Interface returns a dataset without problems (if I comment out the rogue function)

End

Interface

Is this a custom class? The class DarwinObjectModel.DarwinObjectModel.SQLDataSource needs to specify DataContract attribute and all properties exposed need to specify DataMember attribute.

Happy Coding!

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kashif