ASP MVC not displaying proper error pages based on httpErrors configuration

Question

I am using the latest version of ASP.NET MVC 5 for my web application and it is running through IIS 7.5 which came with Windows 7. I am struggling to implement httpErrors in the web.config and to have my breakpoint reached in my error controller.

I have experimented with displaying HTML files and displaying a view from my error controller as error messages. This is my current setup in my web.config:

<system.webServer>
     <httpErrors errorMode="Custom" existingResponse="Replace">
          <remove statusCode="404" subStatusCode="-1" />
          <remove statusCode="500" subStatusCode="-1" />
          <error statusCode="404" path="/Error/Http404" responseMode="ExecuteURL" />
          <error statusCode="500" path="Http500.html" responseMode="File" />
     </httpErrors>
</system.webServer>

I do have an ErrorController class. There is a directory under Views called Error. And in the Error directory are 2 files:

• Http404.cshtml
• Http500.cshtml

When I typed in www.mywebsite.com/foo the following happens:

• The Application_Error method is hit
• The breakpoint in the Http404 action method in my error controller is not hit
• The page displayed to me is white, nothing on it
• Google Chrome shows me that an HTTP 403 forbidden error was thrown

When I typed in www.mywebsite.com/foo.html the following happens:

• The Application_Error method is not hit
• The breakpoint in the Http404 action method in my error controller is not hit
• The page displayed to me is white, nothing on it
• Google Chrome shows me that an HTTP 403 forbidden error was thrown

When I change the the httpErrors configuration to that of below then my static HTML page is displayed with the correct HTTP 404 not found error:

<system.webServer>
     <httpErrors errorMode="Custom" existingResponse="Replace">
          <remove statusCode="404" subStatusCode="-1" />
          <error statusCode="404" path="Http404.html" responseMode="File" />
     </httpErrors>
</system.webServer>

I have nothing in my Application_Error method:

protected void Application_Error(object sender, EventArgs e)
{
     Exception exception = Server.GetLastError();
}

And this what my error controller looks like:

public class ErrorController : Controller
{
     public ActionResult Http404()
     {
          // Not sure if this is needed?
          Response.StatusCode = (int)HttpStatusCode.NotFound;

          return View();
     }

     public ActionResult Http500()
     {
          // Not sure if this is needed?
          Response.StatusCode = (int)HttpStatusCode.InternalServerError;

          return View();
     }
}

I removed the customErrors configuration from the web.config.

I have the following questions:

• How do I get this fixed to display my views in my error controller?
• Why are some errors hitting the Application_Error method and others not?
• How do I know if it is an ASP MVC error or an IIS error?
• Some errors are caught in Application_Error and others not, how do I log all of them?