Question

Catching Own First Chance Exceptions

AppDomain.CurrentDomain.FirstChanceException += FirstChanceException;

private static void FirstChanceException(object sender, System.Runtime.ExceptionServices.FirstChanceExceptionEventArgs e)
    {
        // I would like to log exceptions happening outside my assembly?
        // But this event does not receive external FirstChanceExceptions
        // (unlike Visual Studio debug output)
        myLogger.Log(e.Exception);
    }

Example

• I would like to log A first chance exception of type 'System.IO.IOException' occurred in WindowsBase.dll

• But not log A first chance exception of type 'System.DivideByZeroException' occurred in MyApp.exe

Solution?

• Is there a way to get notified of those exceptions arising in dlls such as mscorlib.dll?
• Note the interest is to log in the production release, not only in debugging.

Why

Exceptions that occur in external dll dependencies can cause trouble, even if they are handled there.

For example, due to an exception a null value may be returned from an external method (instead of returning the desired output of x) and even though my code mostly handles such abnormal output it is useful to know what exactly went wrong and where – because while I may be able to avoid fatal exceptions then more often than not that null value makes part of my app non-functional. So logging the external first chance exception would provide valuable information to help rectify the issue / turn that null into x. And this may be present in only given environments / for specific users etc…

Answer 1

You can use StackTrace class to check what is the source of the exception:

var stackTrace = new StackTrace(e.Exception);
var sourceFrame = stackTrace.GetFrame(0);
var throwingMethod = sourceFrame.GetMethod();
var sourceAssembly = throwingMethod.DeclaringType.Assembly;
var assemblyName = sourceAssembly.GetName().Name;

bool isMyApp = assemblyName == "MyApp";