Custom Error Handling with MVC4

Question

I have a relatively untouched MVC4 project with the following in my Web.Release.config:

<system.web>
<customErrors mode="On" defaultRedirect="~/Error">
  <error redirect="~/Error/NotFound" statusCode="404" />
</customErrors>
</system.web>

It's not working though - I get normal error pages when in Release mode.

If I place that code in my Web.Config, it works as expected. I only want this applied when in Release though.

I also tried this in web.release.config:

  <system.web>
    <customErrors mode="On" defaultRedirect="~/Error" xdt:Transform="Replace">
       <error redirect="~/Error/NotFound" statusCode="404" />
    </customErrors>
    <compilation xdt:Transform="RemoveAttributes(debug)" />
  </system.web>

To no avail.

Why would this be happening?

UPDATE: If I use the following in my global.asax:

    void Application_Error(object sender, EventArgs e)
        {

#if DEBUG
#else
            Response.Redirect("/Error");
#endif
            return;
        }

I get the desired behavior. I feel like I should be able to use the web.config settings only though... so I'd like to leave this open.

Answer 1

The problem is you're not publishing. The web.release.config file is only transformed during publish as far as I know. If you're just building and running locally that file won't be used.

Also in your Application_Error you should get the status code for the error. Something like

var exception = Server.GetLastError();

var httpException = exception as HttpException;

if (httpException != null) 
{
    if (httpException.GetHttpCode() == 404)
        RedirectToMyNotFoundPage();

} 

Otherwise you will basically just handle all errors, which may or may not be what you want to do.

If you want to handle MvcErrors, and get the controller/action that the exception occured in, you should look into Filters.

Here's a good article on error filtering if that's what you're going for.

http://blogs.msdn.com/b/gduthie/archive/2011/03/17/get-to-know-action-filters-in-asp-net-mvc-3-using-handleerror.aspx