Task.Exception
Learn to inspect task errors with Task.Exception.
The Task.Exception property
The Task.Exception property holds the error as an AggregateException when a Task faults. If the Task has not faulted yet, it returns null. This lets you inspect a Task's error without awaiting it.
This is especially useful in fire-and-forget scenarios or when monitoring many Tasks. Example: if (task.Exception != null) { Log(task.Exception); }. Before the Task completes, this property always returns null.
IsFaulted and Exception
Task.IsFaulted gives a bool indicating whether a Task has faulted. Task.IsCompleted tells if the task is done (including faulted). Task.IsCanceled indicates cancellation.
These three flags let you quickly learn a Task's state. If you need error details, look at the Exception property. In fire-and-forget scenarios you can log by watching these flags.
Exercise Inspect Task.Exception
Define static async Task FailAsync(). In its body write await Task.CompletedTask; and throw new InvalidOperationException("Boom");. Make Main a static async Task Main. Call it with Task t = FailAsync(); (do not await yet). Print IsFaulted with try { await t; } catch (Exception) { Console.WriteLine(t.IsFaulted); }.
Show example solution
In FailAsync body write await Task.CompletedTask; and throw new InvalidOperationException("Boom");. Make Main static async Task Main() and write Task t = FailAsync(); try { await t; } catch (Exception) { Console.WriteLine(t.IsFaulted); }
Example solution:
using System;
using System.Threading.Tasks;
class Program
{
static async Task FailAsync()
{
await Task.CompletedTask;
throw new InvalidOperationException("Boom");
}
static async Task Main()
{
Task t = FailAsync();
try
{
await t;
}
catch (Exception)
{
Console.WriteLine(t.IsFaulted);
}
}
}Test yourself
-
What does Task.Exception return?
- AggregateException or null
- The Exception directly
- The Task status
- Bool (whether there is an error)
Show answer
AggregateException or null — Correct. Task.Exception returns AggregateException on fault, null otherwise.
-
Check Task.Exception
if (task.____ != null) { Console.WriteLine("Hata var"); }Show answer
if (task.Exception != null) { Console.WriteLine("Hata var"); } -
When is IsFaulted true?
- While the Task is still running
- When the Task has faulted
- When the Task completes successfully
- When the Task is cancelled
Show answer
When the Task has faulted — Correct. IsFaulted is true only when the task has faulted.