Global.asax Application_Error not firing on IIS

I have an ASP.NET MVC 2 page. During error or exception, the Application_Error method in Global.asax is not firing on IIS7.

**But it does fire if I run the web app from VS2010 (localhost:someport)

My code (C#):

protected void Application_Error(object sender, EventArgs e)
{
  Exception exception = Serve开发者_运维百科r.GetLastError();
  string requestedUrl = HttpContext.Current.Request.Url.ToString();

  Response.Clear();
  // do something
  Server.ClearError();
  Server.Redirect("Error");
}

My config:

<customErrors mode="On" defaultRedirect="~/Error">
</customErrors>

<system.webServer>
  <validation validateIntegratedModeConfiguration="false"/>
  <modules runAllManagedModulesForAllRequests="true" />
</system.webServer>

Please help.

This is because your web config settings are overriding the default behaviour. You will need to disable this (customErrors="Off" and remove the defaultRedirect (or set the correct status codes conditionally which allows unset errors to fall through to the Application_Error event). if you disable this, you can handle the error in the Application_Error event then redirect the user or display a message from this event. This web config setting is handling the errors and only unhandled errors will bubble up to this event.

One more thing.
Application_Error isn't fired for exception that is raised in class/method that is marked HandleError attribute on IIS.
It fires if you run your app on asp.net development server but doesn't work for real IIS. (I fell in this pitfall).