Я обнаружил эту ошибку, когда добавлял свою базу данных в Visual Studio 2010 для создания приложения MVC3.Я использую SQL Server 2008.
The database 'C:\USERS\KAPIL.AGRAWAL\DOCUMENTS\VISUAL STUDIO 2010\PROJECTS\DT\DT\APP_DATA\DTRIAL.MDF'
cannot be opened because it is **version 661**.
This **server supports version 655** and earlier. A downgrade path is not supported.
**Could not open new database** 'C:\USERS\KAPIL.AGRAWAL\DOCUMENTS\VISUAL STUDIO 2010\PROJECTS\DT\DT\APP_DATA\DTRIAL.MDF'.
CREATE DATABASE is aborted.
An attempt to attach an auto-named database for file c:\users\kapil.agrawal\documents\visual studio 2010\Projects\dt\dt\App_Data\dtrial.mdf failed.
A database with the same name exists, or specified file cannot be opened,
or it is located on UNC share.