The task-based asynchronous OperationContract method '{0}' in type '{1}' was matched with the asynchronous OperationContract ...

The task-based asynchronous OperationContract method '{0}' in type '{1}' was matched with the asynchronous OperationContract methods '{2}' and '{3}' because they have the same operation name '{4}'. When a synchronous OperationContract method is matched to a pair of asynchronous OperationContract methods, the two OperationContracts must define the same return type. In this case, the return types are different. To fix it, ensure that method '{0}' and method '{3}' have the same return type. Alternatively, changing the name of one of the methods will prevent matching.