When you call CancelAsync, your application still receives the completion event associated with the operation. For example, when you call CancelAsync to cancel a DownloadUpdateAsync operation, if you have specified an event handler for the DownloadUpdateCompleted event, your event handler receives notification that the operation has ended. To learn whether the operation completed successfully, check the Cancelled property on the AsyncCompletedEventArgs in the event data object passed to the event handler.

If no asynchronous operation is in progress, this method does nothing.

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