I wont get the the aggregate exception is not getting executed
namespace ExceptionTest { class Program { static void Main(string[] args) { Task<int> t1 = new Task<int>(() => Add()); try { t1.Start(); } catch (AggregateException ag) { Console.WriteLine(ag.Message); } Console.ReadLine(); } static int Add() { try { throw new ArgumentException("Exception"); } catch(Exception e) { throw e; } } } } Start() will never throw in a situation like this. It only starts the Task, and immediately returns; it doesn't wait until the Task completes.
If you want to catch the exception, you should use Wait():
Task<int> t1 = Task.Factory.StartNew(() => Add()); try { t1.Wait(); } catch (AggregateException ag) { Console.WriteLine(ag.Message); } And if you use Wait(), you can use Task.Factory.StartNew() (or Task.Run() on .Net 4.5) instead of constructor with Start(). And you also don't need Console.ReadLine() anymore. (Both changes reflected in the above code.)
Task Result will re-throw exception if it thrown earlier in Task execution.