Valore Null restituito da un metodo 'Begin' asincrono o passato a AsyncCallback. Le implementazioni del metodo 'Begin' asincrono devono restituire un valore IAsyncResult non Null e passare lo stesso oggetto IAsyncResult come parametro ad AsyncCallback.

A null value was returned from an async 'Begin' method or passed to an AsyncCallback. Async 'Begin' implementations must return a non-null IAsyncResult and pass the same IAsyncResult object as the parameter to the AsyncCallback.

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