I want await to throw AggregateException, not just the first Exception

Question

When awaiting a faulted task (one that has an exception set), await will rethrow the stored exception. If the stored exception is an AggregateException

Answer 1

I know I'm late but i found this neat little trick which does what you want. Since the full set of exceptions are available with on awaited Task, calling this Task's Wait or a .Result will throw an aggregate exception.

    static void Main(string[] args)
    {
        var task = Run();
        task.Wait();
    }
    public static async Task Run()
    {

        Task[] tasks = new[] { CreateTask("ex1"), CreateTask("ex2") };
        var compositeTask = Task.WhenAll(tasks);
        try
        {
            await compositeTask.ContinueWith((antecedant) => { }, TaskContinuationOptions.ExecuteSynchronously);
            compositeTask.Wait();
        }
        catch (AggregateException aex)
        {
            foreach (var ex in aex.InnerExceptions)
            {
                Console.WriteLine(ex.Message);
            }
        }
    }

    static Task CreateTask(string message)
    {
        return Task.Factory.StartNew(() => { throw new Exception(message); });
    }