The page cannot be returned

The Web server cannot service the request because the requested file is in a format that the server is configured not to download.

Please try the following:

Contact the Web site administrator to inform them that this error has occured for this file type.

HTTP 415 - Unsupported Media Type.
Internet Information Services (IIS)

Technical Information (for support personnel)

Go to Microsoft Product Support Services and perform a title search for the words HTTP and 415.
Open IIS Help, which is accessible in IIS Manager (inetmgr), and search for topics titled Working with MIME Types, Setting Application Mappings, and About Custom Error Messages.