Entityframework：“System.Data.Entity.Internal.AppConfig”的类型初始值设定项引发异常。

   <configSections>
     <!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 -->
     <section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
     <!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 -->
   </configSections>
   <connectionStrings>
     <add name="DefaultConnection" providerName="System.Data.SqlClient" connectionString="Data Source=(LocalDb)\v11.0;Initial Catalog=aspnet-Happy.Shopping-20131211212310;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|\aspnet-Happy.Shopping-20131211212310.mdf" />
     <add name="NavigationUnitOfWork" connectionString="Data Source=(LocalDB)\v11.0;AttachDbFilename=E:\Coding\HappyShopping\Happy.Shopping\Happy.Shopping\App_Data\Shopping.mdf;Integrated Security=True" providerName="System.Data.SqlClient" />
   </connectionStrings>

注意：确定配置文件的版本号和项目引用的版本号匹配。