I have an asp.net application with a HttpModules in it.
It looks at:

AppDomain.CurrentDomain.UnhandledException += new
UnhandledExceptionEventHandler(OnUhe);  //UHE on threads

application.Error += new EventHandler(OnError); //regular UHE

When I put in a URL with a bad location I get an System.Web.HttpException
that is captured in my OnError method.

I would like to capture that this a 404 exception and display something
appropriate.

My HttpModule
has:

      protected virtual void OnError(object sender, EventArgs args)
       {
           HttpApplication application = sender as HttpApplication;

           Exception ex = application.Server.GetLastError() as Exception;

           ProcessTheUHE(ex);
       }

What's interesting though is that Application.Response.StatusCode=200, not
404.  Is my HttpModule messing something up.  Is there a reliable way to
identify that this is a 404?
thanks,

ex.Message

"The file '/Hr-AuthTest/Defaxult.aspx' does not exist."

STACK TRACE

  at System.Web.UI.Util.CheckVirtualFileExists(VirtualPath virtualPath)
  at
System.Web.Compilation.BuildManager.GetVPathBuildResultInternal(VirtualPath
virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean
allowBuildInPrecompile)
  at
System.Web.Compilation.BuildManager.GetVPathBuildResultWithNoAssert(HttpContext
context, VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp,
Boolean allowBuildInPrecompile)
  at
System.Web.Compilation.BuildManager.GetVirtualPathObjectFactory(VirtualPath
virtualPath, HttpContext context, Boolean allowCrossApp, Boolean noAssert)
  at
System.Web.Compilation.BuildManager.CreateInstanceFromVirtualPath(VirtualPath
virtualPath, Type requiredBaseType, HttpContext context, Boolean
allowCrossApp, Boolean noAssert)
  at System.Web.UI.PageHandlerFactory.GetHandlerHelper(HttpContext context,
String requestType, VirtualPath virtualPath, String physicalPath)
  at
System.Web.UI.PageHandlerFactory.System.Web.IHttpHandlerFactory2.GetHandler(HttpContext
context, String requestType, VirtualPath virtualPath, String physicalPath)
  at System.Web.HttpApplication.MapHttpHandler(HttpContext context, String
requestType, VirtualPath path, String pathTranslated, Boolean useAppConfig)
  at
System.Web.HttpApplication.MapHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
  at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean&
completedSynchronously)