Multiple Controllers with one Name in ASP.NET MVC 2

Question

I receive the following error when trying to run my ASP.NET MVC application:

The request for \'Account\' has found the following matching controllers:

Answer 1

A slightly confusing variation on the problem (similar in that it causes the same error message) can occur even with namespaces supplied. MVC 3 I think is a little pickier than MVC 2 on this front.

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Short Answer:

Make sure the namespace of your controller is in fact the namespace specified in the MapRoute call!!

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Long Answer:

I have 3 areas : default ("") / Facebook / Store and they each have AdminController

I have the route mapped like this (for my default area):

routes.MapRoute(
     "Default",
     "{controller}/{action}/{id}",
     new { controller = "Gateway", action = "Index", id = UrlParameter.Optional },
     new string[] { "RR.Controllers.Main" }
);

A request to /admin gave the following error :

Multiple types were found that match the controller named 'admin'. This can happen if the route that services this request ('{controller}/{action}/{id}') does not specify namespaces...

The request for 'admin' has found the following matching controllers:

RR.FacebookControllers.AdminController
RR.Controllers.AdminController
RR.StoreControllers.AdminController

But wait a minute! Didn't I specify the controller namespace.... ? What's going on.... ?

Well it turned out my default area's admin controller namespace was RR_MVC.Controller instead of Rolling_Razor_MVC.Controller.Main.

For some reason in MVC 2 this didn't give a problem, but in MVC 3 it does. I think MVC 3 just requires you to be more explicit when there's potential ambiguities.