System.Data.Entity.Core.ProviderIncompatibleException

这是课程

public class Order
{
    public virtual int OrderID { get; set; }
}

上下文文件

public ShoppingCartContext() : base("ShoppingCartDb")
{
        Database.SetInitializer<ShoppingCartContext>(new DropCreateDatabaseAlways<ShoppingCartContext>());
}

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
        #region Entity Framework 6 RC-1
        modelBuilder.Properties().Where(x => x.Name == x.DeclaringType.ToString() + "ID")
                .Configure(x => x.IsKey());

        modelBuilder.Properties<DateTime>()
                .Configure(x => x.HasColumnType("datetime2"));
        #endregion

        modelBuilder.Conventions.Remove<PluralizingTableNameConvention>();
        base.OnModelCreating(modelBuilder);
    }

和connctionstring的web.config文件部分

<connectionStrings>
   <add name="ShoppingCartDb" 
        connectionString="Server=Localhost;Database=ShoppingCartEfDb;User Id=sa;Password=xxxxxxxxxx" 
        providerName="System.Data.sqlClient" />
</connectionStrings>

每当我尝试添加迁移时,我都会收到错误：

System.Data.Entity.Core.ProviderIncompatibleException: An error occurred while getting provider information from the database. This can be caused by Entity Framework using an incorrect connection string. Check the inner exceptions for details and ensure that the connection string is correct. —> System.Data.Entity.Core.ProviderIncompatibleException: The provider did not return a ProviderManifestToken string. —>

System.Data.sqlClient.sqlException: A network-related or instance-specific error occurred while establishing a connection to sql Server. The server was not found or was not accessible. Verify that the instance name is correct and that sql Server is configured to allow remote connections. (provider: sql Network Interfaces,error: 26 – Error Locating Server/Instance Specified)