[solved]A route named 'Admin_default' is already in the route collection. Route names must be unique.

In this article I describe how to solve.This problem was faced when I need to create new project with the help of old project. I have copied old project and paste it specified location. I made changes on the copied project as per requirement while running the project I faced this problem. Latterly I found the solution by deleting all DLL files in bin folder and rebuild the solution problem fixed.

A route named 'Admin_default' is already in the route collection.Route names must be unique.
Parameter name: name

Description: Anunhandled exception occurred during the execution of the current web request.Please review the stack trace for more information about the error and where itoriginated in the code. 
Exception Details: System.ArgumentException:A route named 'Admin_default' is already in the route collection. Route namesmust be unique.
Parameter name: name

Source Error: 

Line 15:         public override void RegisterArea(AreaRegistrationContext context)

Line 16:         {

Line 17:             context.MapRoute(

Line 18:                 "Admin_default",

Line 19:                 "Admin/{controller}/{action}/{id}",

Source File: m:\MVCSQL\chiptrolls\twitter_karimfi\twitter_karimfi\Areas\Admin\AdminAreaRegistration.cs    Line: 17