Task.WaitAll Method (Task, TimeSpan)
Waits for all of the provided Task objects to complete execution.
Assembly: mscorlib (in mscorlib.dll)
One or more of the Task objects in tasks has been disposed.
The tasks argument is null.
At least one of the Task instances was canceled -or- an exception was thrown during the execution of at least one of the Task instances. If a task was canceled, the AggregateException contains an in its InnerExceptions collection.
timeout is a negative number other than -1 milliseconds, which represents an infinite time-out -or- timeout is greater than MaxValue.
The tasks argument contains a null element.
For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.