Exception in async methods is not caught

Question

The following code does not catch my OperationCancelException which is thrown by calling ct.ThrowIfCancellationRequested.

public partial class Title         


        

Answer 1

In your first example the exception is not caught because it does not occure before leaving the try/catch block. If you want to catch it there you need to wait/await it there exactly like you do in the second example. If you do not await the returned task the method continues execution and leaves the try/catch block before the exception actually occures...

If you want to catch the exception "out of band" you can also register to TaskScheduler.UnobservedTaskException (this event is called if a task is throwing an exception which is nowhere caught) to get all uncaught exceptions or monitor the tasks Exception property. May also check out THIS answer.

Answer 2

Exeption is thrown in the task on another thread.

public async Task GetCancelExceptionAsync(CancellationToken ct)
        {
            try
            {
                await Task.Delay(1000);
                ct.ThrowIfCancellationRequested();
            }
            catch (Exception e)
            {
                // your Cancleation expeption
            }
        }