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

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