using System;

using System.Threading.Tasks;

using System.Linq;

public class Program

{

    public static async Task Main()

    {

        var task1 = Bla();

        var task2 = Bla1();

​

        var allTask = Task.WhenAll(task1, task2);

        try{

            await allTask;

        }

        catch(Exception)

        {

            string.Join(", ", allTask.Exception.Flatten().InnerExceptions.Select(e => e.Message)).Dump();

        }

    }

​

    public static Task Bla()

    {

        return Task.Run(() => throw new Exception("Exception"));

    }

​

    public static Task Bla1()

    {

        return Task.Run(() => throw new ArgumentException("ArgumentException"));

    }

}