using System;

using System.Threading;

using System.Threading.Tasks;

using System.Linq;

​

public static class Program

{

    public static void Main()

    {

        var task1 = Task.FromResult(13);

        var task2 = Task.FromCanceled<int>(new CancellationToken(true));

        var task3 = Task.FromCanceled<int>(new CancellationToken(true));

        var task4 = Task.FromException<int>(new ApplicationException());

        var task5 = Task.FromException<int>(new OverflowException());

        //var task5 = Task.FromException<int>(new OperationCanceledException());

        Test("Successful+Canceled+Canceled", new[] { task1, task2, task3 });

        Test("Successful+Failed+Failed", new[] { task1, task4, task5 });

        Test("Successful+Canceled+Failed+Failed", new[] { task1, task2, task4, task5 });

        Test("Successful+Canceled+Canceled+Failed", new[] { task1, task2, task3, task4 });

​

        static void Test(string title, Task<int>[] tasks)

        {

            Console.WriteLine();

            Console.WriteLine(title);

            try { Task.WaitAll(tasks); }

            catch (AggregateException ex)

            {

                Console.WriteLine($"WaitAll():      {ToString(ex)}");

            }

            try { Task.WhenAll(tasks).Wait(); }

            catch (AggregateException ex)

            {

                Console.WriteLine($"WhenAll.Wait(): {ToString(ex)}");

            }

        }

​

        static string ToString(AggregateException aex) {

            return $"({aex.InnerExceptions.Count}) " + String.Join(", ", aex.InnerExceptions.Select(ex => ex.GetType().Name));

        }

    }

}

​