Stacktrace reported by UnhandledExceptionEventArgs exception becomes null after extracting once

Question

I have a Windows Phone 8.1 RT application. In the app, I subscribe to UnhandledException event which is raised when any unhandled exception occurs in the application. I bind this event to an event handler, which is passed UnhandledExceptionEventArgs by the event.

UnhandledExceptionEventArgs has a property Exception, which has a property Stacktrace. The problem is, I'm only able to access the stacktrace property only once, as it becomes null after I access it.

This weird behavior can also be observed when any breakpoint is hit and you try to access the value contained in the argument using the cursor or the immediate window. Once I hover the cursor or access the value in the immediate window, it becomes null afterwards.

It also causes an issue when I read any property of UnhandledExceptionEventArgs before reading the Stacktrace property. Say, if e is of type UnhandledExceptionEventArgs containing Message and Exception object, accessing e.Message before accessing e.Exception.Stacktrace makes the value contained in e.Exception.Stacktrace null.

Any idea why this odd behavior is observed?

Answer 1

Not sure if this is the case, but MSDN says:

The UnhandledException event arguments expose an exception object through the Exception property. However, the type, message, and stack trace of this exception object are not guaranteed to match those of the original exception that was raised

Answer 2

This seems to be an issue: Improper WinRT exception behavior

You should save UnhandledExceptionEventArgs.Exception value to a variable before reading any properties of UnhandledExceptionEventArgs class. After that you can access any information (like stack trace) at any moment by reading your variable value(not UnhandledExceptionEventArgs.Exception value).