Coding⏱️ 2 min read📅 2026-05-31

How to Fix: A route named "x" is already in the route collection. Route names must be unique. Exception with ASP.NET MVC 3

Duplicate route names must be unique in ASP.NET MVC 3.

Quick Answer: Check for duplicate route names and remove the redundant one to resolve the exception.

The exception 'A route named '' is already in the route collection. Route names must be unique.' occurs when you try to add a duplicate route name to your ASP.NET MVC application.

🛑 Root Causes of the Error

  • Using the same route name in multiple controllers or actions.

🔧 Proven Troubleshooting Steps

Method 1: Check for Duplicate Route Names

  1. Step 1: Open the RouteConfig.cs file and review all route definitions.

Method 2: Use Unique Route Names

  1. Step 1: Update all route names to be unique and descriptive.

🎯 Final Words

To resolve this issue, simply review your route definitions and update any duplicate or non-descriptive names. This will ensure that all routes are unique and functioning correctly.

Did this fix your problem?

If not, try searching for specific error codes.

🔍 Search Error Database

❓ Frequently Asked Questions