This seems like a question that has already been asked/answered many times. Its not.
Development Environment: VS 2012 and MVC 4. I am using the buil
I encountered the same problem. To solve is very easy.
This problem occurs because of an IIS Express conflict when you edit the properties in the Protect URL in the Project settings. To solve this problem is very easy:
1 - Look for the file "applicationhost.config" in the ".vs \ config" directory. This folder is at the root of the solution. You can open it using Notepad ++
2 - Search for the name of your control using 'find' of your program (Ctrl + F). In my case, the control that gave problem was the 'Offices'.
3 - Delete any node where you place the IIS settings for such a URL. See example below:
You should delete every element
Note: Make a backup of the file before making the changes.
Hugs