I ran into the following problem after changing the namespace for my mvc project:
Multiple types were found that match the controller named 'Home'. This can happen if the route that services this request ('{controller}/{action}/{id}') does not specify namespaces to search for a controller that matches the request. If this is the case, register this route by calling an overload of the 'MapRoute' method that takes a 'namespaces' parameter.
The request for 'Home' has found the following matching controllers:
oldns.Controllers.HomeController
newns.Controllers.HomeController
There are other answered questions about this error, but cover other causes: