ASP.net MVC [HandleError] not catching exceptions

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In two different application, one a custom the other the sample MVC application you get with a new VS2008 MVC project, [HandleError] is not catching exceptions.

In the sample application I have: 

[HandleError]
public class HomeController : Controller
{
    public ActionResult Index()
    {
        ViewData["Message"] = "Welcome to ASP.NET MVC!";
        throw new Exception();
        return View();
    }

    public ActionResult About()
    {
        return View();
    }
}

which is just the default controller with an exception being thrown for testing.

But it doesn't work. Instead of going to the default error.aspx page it shows the debug information in the browser.

The problem first cropped up in a custom application I'm working on which led me to test it with the sample application. Thinking it had something to do with changes I made in the custom application, I left the sample application completely unchanged with the exception (yuck) of the throw in the index method.

I'm stumped. What am I missing?

handleerror exception-handling asp.net-mvc
6 Answers

In Web.config, change customErrors:

<system.web>
  <customErrors mode="On">
  </customErrors>

If mode is either Off or RemoteOnly, then you will see the yellow screen of death instead of the custom error page. The reasoning is that developers usually want the more detailed information on the yellow screen of death.

Craig_Stuntz_77140

Important: Be careful that your error page itself does not have an error on it!

If it does you'll end up with that ASP.NET custom error page and end up going round in circles and tearing your hair out. Just strip everything out of the page that could possibly cause an error and test it.

Also with respect to 'customErrors' being ON or OFF there are several contributing factors to whether or not the friendly error page (your Errors.aspx) page will be shown or not.

See this blog (except below)

HttpContext.IsCustomErrorEnabled - looks at three different sources

  1. The web.config's <deployment> section's retail property. This is a useful property to set when deploying your application to a production server. This overrides any other settings for custom errors.
  2. The web.config's <customErrors> section's mode property. This setting indicates whether custom errors are enabled at all, and if so whether they are enabled only for remote requests.
  3. The HttpRequest object's IsLocal property. If custom errors are enabled only for remote requests, you need to know whether the request is from a remote computer.

The idea here is that you can have 'customErrors' turned OFF during development - when you do want to see the errors, and then enable it for production only.

This MSDN article discusses the attribute further.

Simon_169400

Another reason for this problem may be ,

In Template MVC Application (generated by VS2008 / VS2008 Express) , Error.aspx (generated by VS) uses Master Page.

If Master Page access any ViewData it will throw null reference Exception , then the error.aspx won't be shown.

Use this Simple code as your Error.aspx , it will solve the problem, (along with CustomErrors=On )

<%@ Page Language="C#"  Inherits="System.Web.Mvc.ViewPage<System.Web.Mvc.HandleErrorInfo>" %>
<%= Model.Exception.Message %>
user_736300

There is some silly situation which once happened with me, so might be helpfull for someone.

Be sure that you've added <customErrors mode="On" /> to the correct web.config file.

Sometimes (especially, when you work with something like Resharper, and open your files with typing their name, but not via Solution Explorer), you can simply open a web.config either from Views folder or even from another project.

user_6916600
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