/Admin/Manager.WebApp/Global.asax.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Http;
using System.Web.Mvc;
using System.Web.Optimization;
using System.Web.Routing;

using Manager.SharedLibs.Logging;
using Manager.WebApp.Controllers;

using Newtonsoft.Json;

namespace Manager.WebApp
{
    public class MvcApplication : System.Web.HttpApplication
    {
        private readonly ILog logger = LogProvider.GetCurrentClassLogger();

        protected void Application_Start()
        {
            AreaRegistration.RegisterAllAreas();
            FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
            GlobalConfiguration.Configure(WebApiConfig.Register);
            RouteConfig.RegisterRoutes(RouteTable.Routes);
            BundleConfig.RegisterBundles(BundleTable.Bundles);

            //This value provider will handle requests that are encoded as application/json. 
            //There’s no need to specify a model binder on classes that accept JSON input.
            //ValueProviderFactories.Factories.Add(new JsonValueProviderFactory());
            System.Web.Helpers.AntiForgeryConfig.SuppressXFrameOptionsHeader = true;
        }


        protected void Application_Error(object sender, EventArgs e)
        {            
            var httpContext = ((MvcApplication)sender).Context;

            var currentRouteData = RouteTable.Routes.GetRouteData(new HttpContextWrapper(httpContext));
            var currentController = " ";
            var currentAction = " ";

            if (currentRouteData != null)
            {
                if (currentRouteData.Values["controller"] != null && !String.IsNullOrEmpty(currentRouteData.Values["controller"].ToString()))
                {
                    currentController = currentRouteData.Values["controller"].ToString();
                }

                if (currentRouteData.Values["action"] != null && !String.IsNullOrEmpty(currentRouteData.Values["action"].ToString()))
                {
                    currentAction = currentRouteData.Values["action"].ToString();
                }
            }

            var ex = Server.GetLastError();

            var currentAreaRoute = HttpContext.Current.Request.RequestContext.RouteData.DataTokens["area"];

            var currentArea = string.Empty;

            if (currentAreaRoute != null)
                currentArea = currentAreaRoute.ToString();

            if (currentArea.Contains("admin") || currentArea.Contains("Admin"))
            {
                var controller = new ErrorController();
                var routeData = new RouteData();
                var action = "Index";

                if (ex is HttpException)
                {
                    var httpEx = ex as HttpException;

                    switch (httpEx.GetHttpCode())
                    {
                        case 404:
                            action = "NotFound";
                            break;

                        // others if any
                        default:
                            action = "Index";
                            break;
                    }
                }

                logger.ErrorException("Application Error: {0}", ex, ex.Message);

                httpContext.ClearError();
                httpContext.Response.Clear();
                httpContext.Response.StatusCode = ex is HttpException ? ((HttpException)ex).GetHttpCode() : 500;
                httpContext.Response.TrySkipIisCustomErrors = true;

                //Process error for Ajax Request
                //http://stackoverflow.com/questions/7551424/how-to-know-if-the-request-is-ajax-in-asp-net-in-application-error
                bool isAjaxCall = string.Equals("XMLHttpRequest", Context.Request.Headers["x-requested-with"], StringComparison.OrdinalIgnoreCase);
                Context.ClearError();
                if (isAjaxCall)
                {
                    var jsonObject = new { error = true, message = ex.Message };
                    var jsonStringResponse = JsonConvert.SerializeObject(jsonObject);

                    Context.Response.ContentType = "application/json";
                    Context.Response.Write(jsonStringResponse);

                    return;
                }

                routeData.Values["controller"] = "../Areas/Admin/Views/Error";
                routeData.Values["action"] = action;

                //Response.TrySkipIisCustomErrors = true; // If you are using IIS7, have this line
                //IController errorsController = new ErrorController();
                //HttpContextWrapper wrapper = new HttpContextWrapper(Context);
                //var rc = new System.Web.Routing.RequestContext(wrapper, routeData);
                //errorsController.Execute(rc);

                //IController controller = new ErrorController();
                //controller.Execute(new RequestContext(new HttpContextWrapper(Context), routeData));
                //Response.End();

                controller.ViewData.Model = new HandleErrorInfo(ex, currentController, currentAction);
                ((IController)controller).Execute(new RequestContext(new HttpContextWrapper(httpContext), routeData));
                Response.End();
            }
            else
            {
                var controller = new ErrorController();
                var routeData = new RouteData();
                var action = "Index";

                if (ex is HttpException)
                {
                    var httpEx = ex as HttpException;

                    switch (httpEx.GetHttpCode())
                    {
                        case 404:
                            action = "NotFound";
                            break;

                        // others if any
                        default:
                            action = "Index";
                            break;
                    }
                }

                logger.ErrorException("Application Error: {0}", ex, ex.Message);

                httpContext.ClearError();
                httpContext.Response.Clear();
                //httpContext.Response.StatusCode = ex is HttpException ? ((HttpException)ex).GetHttpCode() : 500;
                //httpContext.Response.TrySkipIisCustomErrors = true;

                //Process error for Ajax Request
                //http://stackoverflow.com/questions/7551424/how-to-know-if-the-request-is-ajax-in-asp-net-in-application-error
                bool isAjaxCall = string.Equals("XMLHttpRequest", Context.Request.Headers["x-requested-with"], StringComparison.OrdinalIgnoreCase);
                Context.ClearError();
                if (isAjaxCall)
                {
                    var jsonObject = new { error = true, message = ex.Message };
                    var jsonStringResponse = JsonConvert.SerializeObject(jsonObject);

                    Context.Response.ContentType = "application/json";
                    Context.Response.Write(jsonStringResponse);

                    return;
                }

                routeData.Values["controller"] = "Error";
                routeData.Values["action"] = action;

                //Response.TrySkipIisCustomErrors = true; // If you are using IIS7, have this line
                //IController errorsController = new ErrorController();
                //HttpContextWrapper wrapper = new HttpContextWrapper(Context);
                //var rc = new System.Web.Routing.RequestContext(wrapper, routeData);
                //errorsController.Execute(rc);

                //IController controller = new ErrorController();
                //controller.Execute(new RequestContext(new HttpContextWrapper(Context), routeData));
                //Response.End();

                controller.ViewData.Model = new HandleErrorInfo(ex, currentController, currentAction);
                ((IController)controller).Execute(new RequestContext(new HttpContextWrapper(httpContext), routeData));
                Response.End();
            }
        }

    }
}