using System;

using System.Threading.Tasks;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Catch in an async method");

        CatchInAsync().Wait();

        Console.WriteLine();

        Console.WriteLine("Catch in an sync method");

        CatchInSync();

    }

    private static void CatchInSync()

    {

        try {

            var whenAllTask = Task.WhenAll(

                ThrowStuff(1, true),

                ThrowStuff(2, true));

            whenAllTask.Wait();

        }

        catch (Exception ex) {

            Console.WriteLine(ex);

        }

    }

    private static async Task CatchInAsync()

    {

        try {

            var whenAllTask = Task.WhenAll(

                ThrowStuff(1, true),

                ThrowStuff(2, true));

            await whenAllTask;

        }

        catch (Exception ex) {

            Console.WriteLine(ex);

        }

    }

    private static async Task ThrowStuff(int index, bool throwException)

    {

        Console.WriteLine("Task: " + index + " started");

        await Task.Delay(10);

        if (throwException)

            throw new Exception("Boom! " + index);

    }

}

​