观察到的任务异常调用TaskScheduler.UnobservedTaskException

Question

My App is .NET 4.5 and I have a event handler that logs all error on unobserved task exceptions.

TaskScheduler.UnobservedTaskException += (sender, e) => e.Exception.Handle(ex =>
{
    logger.Error(e.Exception);
    return false;
});

I return false, what shuts down the application. Simulating the .NET 4.0 behavior.

My question is, why this code calls the event and consequently crash my app if I am observing the result?

try
{
    var resultado = httpClient.GetAsync('http://.....').Result;
}
catch (Exception ex)
{
    logger.Error(ex);
}

UPDATE: After some debugging, I figure out that I had another Task when I didn´t called .Result and was causing the problem.

Answer 1

You're supposed to set UnobservedTaskExceptionEventArgs.Observed to true. Observing the result at this point has no effect, although one might reasonably believe that it does.

Answer 2

经过一些调试后，我发现当我没有调用.Result并导致问题时，我还有另一个任务。