Getting Started:

    By default if we get any exception while running our code, we are redirected to a Yellow Screen Of Death, containing the details of the error.

Example:

public class HomeController : Controller
{
    // ...

    public ActionResult About()
    {
        throw new Exception("This is not good. Something bad happened.");
    }
}

By default this code will give us the following Yellow Screen Of Death.

But if we wan't to display a Custom Error page then:

Step 1: Write the following code in your web.config file:

<system.web>
  <customErrors mode="On" defaultRedirect=~/BadError.htm"/>
</system.web>

This will set your custom error mode 'ON' and will always redirect you to "~/Views/Shared/Error.cshtml " on every exception.

Step 2: Now we can write our own content at "~/Views/Shared/Error.cshtml". By default the 'Error.cshtml' will look like:

@model System.Web.Mvc.HandleErrorInfo

@{
    ViewBag.Title = "Error";
}

<h1 class="text-danger">Error.</h1>
<h2 class="text-danger">An error occurred while processing your request.</h2>

We can write the description of the exception as follows:

@model System.Web.Mvc.HandleErrorInfo

@{
    ViewBag.Title = "Error";
}

<h2>
    Sorry, an error occurred while processing your request.
</h2>
<p>Controller = @Model.ControllerName</p>
<p>Action = @Model.ActionName</p>
<p>Message = @Model.Exception.Message</p>
<p>StackTrace :</p>
<pre>@Model.Exception.StackTrace</pre>

Now incase of exceptions it will be redirected to the "~/Views/Shared/Error.cshtml", but incase of errors such as "404 page not found", etc. it will be redirected to the path defaultRedirect=~/BadError.htm" taken from <customErrors mode="On" defaultRedirect = ~/BadError.htm"/>

Note:-> If we wan't to redirect to different error pages for errors with different status code then write the following code in your Web.Config file:

<system.web>
  <customErrors mode="On" defaultRedirect=~/BadError.htm">
     <error redirect="~/MultipleSubmit/FileUpload" statusCode="404" />
     //...
  </customErrors>
</system.web>

This will redirect to "~/MultipleSubmit/FileUpload" for Error with status code 404.Similarly we can declare redirect actions for other status codes also.

But if we don't want to redirect to "~/Views/Shared/Error.cshtml" and wan't to go some other view then:

Step 1: Write the following code in your web.config file:

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

Step 2: Goto FilterConfig.cs in App_Start folder, you will find the following code:

using System.Web;
using System.Web.Mvc;

namespace MultipleSubmit
{
    public class FilterConfig
    {
        public static void RegisterGlobalFilters(GlobalFilterCollection filters)
        {
            filters.Add(new HandleErrorAttribute());
        }
    }
}

Edit the above code as :

using System.Web;
using System.Web.Mvc;

namespace MultipleSubmit
{
    public class FilterConfig
    {
        public static void RegisterGlobalFilters(GlobalFilterCollection filters)
        {
            filters.Add(new HandleErrorAttribute{ View = "Name of the view" });
        }
    }
}

Now whenever the exception will occur, it will be redirected to the View mentioned in the above code and not to the "~/Views/Shared/Error.cshtml".