How do I setup a global exception handler for my application?

From Guidance Share

J.D. Meier, Prashant Bansode, Alex Mackman

Answer

To set up a global exception handler for your application, write your exception handling code in the Application_Error event handler that is implemented in Gloabal.asax. This event is raised when exceptions are allowed to propagate from page-level error handlers or if there is no page error handler. Ideally, the exception handling code you write in the Application_Error method will collect and log as much exception details necessary for you to diagnose the error. An unhandled exception might leave your application in an unstable and un-usable form, hence as a fall back mechanism you should always implement a global exception handler. A sample global exception handler that writes exception details to the event log is shown below:

<%@ Application Language="C#" %>
<%@ Import Namespace="System.Diagnostics" %>

<script language="C#" runat="server">
void Application_Error(object sender, EventArgs e)
{
  //get reference to the source of the exception chain
  Exception ex = Server.GetLastError().GetBaseException(); 

  //log the details of the exception and page state to the
  //Event Log
  EventLog.WriteEntry("My Web Application",
    "MESSAGE: " + ex.Message + 
    "\nSOURCE: " + ex.Source +
    "\nFORM: " + Request.Form.ToString() + 
    "\nQUERYSTRING: " + Request.QueryString.ToString() +
    "\nTARGETSITE: " + ex.TargetSite +
    "\nSTACKTRACE: " + ex.StackTrace, 
    EventLogEntryType.Error);

  //Optional email or other notification here...
}
</script>