The page you are requesting cannot be served because of the extension
configuration. If the page is a script, add a handler. If the file should be
downloaded, add a MIME map.
My first experiences with Server 2012 had me puzzled for a few mins when trying to get some WCF service end points transferred from another older 2003 server.
It was solved by going into server manager, drilling down in the add roles and features to the server concerned, selecting Features. under the .NET Framework 4.5 features there was WCF Services, after checking the box and under that also selecting HTTP Activation to on, everything sprang to life.
There are also 3.5 versions of these too if the application is running on the older framework.