Logging unhandled exceptions to a log file

Question

How can I log unhandled exceptions to a log file for a WinForms application so it is easy to determine the source of an exception?

Answer 1

Firstly, you will need to catch unhandled exceptions. Add the VB.Net version of this code to your main program:

Application.SetUnhandledExceptionMode(UnhandledExceptionMode.CatchException);
Application.ThreadException += ApplicationThreadException;
AppDomain.CurrentDomain.UnhandledException += UnhandledExceptionHandler;

Then add the event handlers:

static void UnhandledExceptionHandler(object sender, UnhandledExceptionEventArgs e)
{
    Exception ex = e.ExceptionObject as Exception;
    if (ex != null)
    {
       Console.WriteLine("Unhandled exception: {0}", e.Exception);      
    }
}

static void ApplicationThreadException(object sender, ThreadExceptionEventArgs e)
{
    Console.WriteLine("Unhandled application exception: {0}", e.Exception);
}

Then you can log the errors with your chosen log method.. (Sorry for the C# code!)

Answer 2

In your Sub Main, or the constructor for your start up form, add the following code:

AddHandler AppDomain.CurrentDomain.UnhandledException, AddressOf UnhandledExceptionHandler

Then, add the following method to your Sub Main, or add it as a shared method in any other class/form:

Public Sub UnhandledExceptionHandler(ByVal sender As Object, ByVal e As UnhandledExceptionEventArgs)
    If TypeOf e.ExceptionObject Is Exception Then
        Dim ex As Exception = CType(e.ExceptionObject, Exception)
        ' Log the exception
    End If
End Sub