A route named 'MS_attributerouteWebApi' is already in the route collection

Question

I recently added Microsoft.AspNet.WebApi.WebHost to a MVC WebAPI project which would allow me to use the [Route("api/some-action")] attribute on my action. I solved some errors using this article but can't solve the third error below. Added solved errors below to get feedback if I did anything wrong.

First Error: No action was found on the controller 'X' that matches the name 'some-action'
Solution: Added config.MapHttpAttributeRoutes(); to WebApiConfig.cs Register method.

Second Error: System.InvalidOperationException The object has not yet been initialized. Ensure that HttpConfiguration.EnsureInitialized() is called in the application's startup code after all other initialization code.
Solution: Added GlobalConfiguration.Configure(WebApiConfig.Register); to Global.asax.cs Application_Start

Third Error: System.ArgumentException: A route named 'MS_attributerouteWebApi' is already in the route collection. Route names must be unique.
Solution = ?

I've already tried cleaning and deleting all DLLs from bin folder according to this post.

score 45 · Answer 1 · answered Mar 12 '15 at 16:02

45

I had a similar problem and it was related to a copy paste error on my part where I added a copy of this line in my WebApiConfig.cs file:

config.MapHttpAttributeRoutes();

make sure you only have one of these.

answered Mar 12 '15 at 16:02

BraveNewMath

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or like me duplication was in Global.asax.cs with GlobalConfiguration.Configure(config => config.MapHttpAttributeRoutes()) – Iman Apr 09 '17 at 05:26

JoeyZhao · Answer 2 · 2017-09-09T01:25:12.140

18

In the Global.asax, check how many times WebApiConfig.Register function has been called.

edited Sep 09 '17 at 01:25

answered Feb 12 '16 at 20:42

JoeyZhao

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score 7 · Answer 3 · answered Oct 15 '14 at 19:28

7

Solved! Removed the line WebApiConfig.Register(GlobalConfiguration.Configuration); from Global.asax.cs Application_Start.

answered Oct 15 '14 at 19:28

joym8

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GlobalConfiguration.Configure(WebApiConfig.Register); was the first line in my global.asax and it seems to be doing the same thing. – Jhonny D. Cano -Leftware- Oct 20 '15 at 16:17

score 7 · Answer 4 · answered Dec 16 '14 at 18:58

7

I have solved by cleaning the deployment directory before copy the new files. Probably there was some old file that try to register the same root multiple times.

answered Dec 16 '14 at 18:58

Davide Icardi

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I had rogue DLLs in my bin folder after a project rename. Cleaning the project didn't help, so I had to delete the DLLs manually through Explorer – oscilatingcretin Jan 12 '17 at 10:00
I really hate this kind of solution, but in this case. works. – AFetter Mar 07 '17 at 04:48

score 3 · Answer 5 · answered Jun 15 '19 at 12:17

I had the same issue and I discovered that in WebApiConfig.cs and after I added configuration for API version

I have those two lines

config.MapHttpAttributeRoutes(constraintResolver);

config.MapHttpAttributeRoutes();

I removed the second line

the final code is

 public static class WebApiConfig
{
    public static void Register(HttpConfiguration config)
    {

        // Web API routes
        var constraintResolver = new DefaultInlineConstraintResolver()
        {
            ConstraintMap =
            {
                ["apiVersion"] = typeof( ApiVersionRouteConstraint )
            }
        };
        config.MapHttpAttributeRoutes(constraintResolver);
        config.AddApiVersioning();

        // Web API configuration and services

        // Web API routes
       // config.MapHttpAttributeRoutes();

        config.Routes.MapHttpRoute(
            name: "DefaultApi",
            routeTemplate: "api/{controller}/{id}",
            defaults: new { id = RouteParameter.Optional }
        );


    }
}

score 2 · Answer 6 · answered Jul 13 '15 at 13:24

For anybody stumbling across this as I did, this error will happen if you rename the Assembly name (project properties). In my case I was renaming a project, and went into the properties to change the assembly name (which VS2013 won't do for you).

Because the assembly name is different, a Clean or Rebuild will not remove the "old" assembly if it is in the \bin folder. You have to delete the assembly from the \bin folder, then rebuild & run.

score 2 · Answer 7 · answered Nov 20 '17 at 14:42

Probably you have same register more than one.

Try to delete below codes from Global.asax:

GlobalConfiguration.Configure(WebApiConfig.Register);
  RouteConfig.RegisterRoutes(RouteTable.Routes);

and write this ones instead of them :

GlobalConfiguration.Configuration.EnsureInitialized(); BundleConfig.RegisterBundles(BundleTable.Bundles);

I am not sure about reason; but it worked for me in my same case.

score 0 · Answer 8 · answered Jan 04 '16 at 20:45

I was also experiencing a similar problem (not the MS_attributerouteWebApi route in particular, but a different named route). After verifying only one config.MapHttpAttributeRoutes() existed, began realizing that MapHttpAttributeRoutes will register all project assemblies including externally referenced ones. After finding out that I had a referenced assembly that was registering its own routes, I found a way to exclude or "skip over" routes by overriding the DefaultDirectRouteProvider:

/// <summary>
/// Allows for exclusion from attribute routing of controllers based on name
/// </summary>
public class ExcludeByControllerNameRouteProvider : DefaultDirectRouteProvider {

    private string _exclude;
    /// <summary>
    /// Pass in the string value that you want to exclude, matches on "ControllerType.FullName" and "ControllerType.BaseType.FullName"
    /// </summary>
    /// <param name="exclude"></param>
    public ExcludeByControllerNameRouteProvider(string exclude) {
        _exclude = exclude;
    }

    protected override IReadOnlyList<RouteEntry> GetActionDirectRoutes(
    HttpActionDescriptor actionDescriptor,
    IReadOnlyList<IDirectRouteFactory> factories,
    IInlineConstraintResolver constraintResolver)
    {
        var actionRoutes = new List<RouteEntry>();
        var currentController = actionDescriptor.ControllerDescriptor.ControllerType;
        if (!currentController.FullName.Contains(_exclude) && !currentController.BaseType.FullName.Contains(_exclude))
        {
            var result = base.GetActionDirectRoutes(actionDescriptor, factories, constraintResolver);
            actionRoutes = new List<RouteEntry>(result);
        }
        return actionRoutes.AsReadOnly();
    }
}

This allows for you to pass a Controller name or Base Type name in to exclude in your WebApiConfig.cs like:

config.MapHttpAttributeRoutes(new ExcludeByControllerNameRouteProvider("Controller.Name"));

Whether or not directly related, hoping this snippet can help!

score 0 · Answer 9 · answered Mar 08 '19 at 21:02

0

I was experiencing the same problem. The solution I found was that I needed visual basic support for mono. When I executed "yum install mono-basic" and restarted my computer the error went away.

answered Mar 08 '19 at 21:02

DonM

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1

score 0 · Answer 10 · edited Jun 07 '19 at 10:35

In my case error was : "A route named 'MS_attributerouteWebApi' is already in the route collection. Route names must be unique. Parameter name: name"

Code was:

public static void Register(HttpConfiguration config)
        {
            // Web API configuration and services

            config.MapHttpAttributeRoutes();  // this line had issue

            var constraintResolver = new DefaultInlineConstraintResolver();
            constraintResolver.ConstraintMap.Add("nonzero", typeof(NonZeroConstraint));
            config.MapHttpAttributeRoutes(constraintResolver);

            config.Routes.MapHttpRoute(
                name: "DefaultApi",
                routeTemplate: "api/{controller}/{id}",
                defaults: new { id = RouteParameter.Optional }
            );
        }

Solution : I just removed - config.MapHttpAttributeRoutes(); line from above method and it got resolved.

A route named 'MS_attributerouteWebApi' is already in the route collection

10 Answers10