We had a MVC application moved to a new server. .NET 4 and MVC 3 was installed, but we still got “Error 403.14”. In this case, this meant that IIS did not understand that it was dealing with a MVC application, it was looking for the default page.
The solution was simple: HTTP Redirection was not installed on the server.
Server Manager – Roles – Web Server (IIS) – Roles Services – HTTP Redirection: Not installed. Installed it, problem solved.