The underlying provider failed on Open

Feb 3, 2012 at 2:34 AM

When I run the MVC3Demo, it throws exception "The underlying provider failed on Open" in the line of code below:

    public class OrdersController : Controller    {        public ActionResult Index(int id = 1)        {            using (var db = new OrderEntities())            {                PagedList<Order> orders = db.Orders.OrderBy(o=>o.OrderID).ToPagedList(id, 20);

Does anyone know what happened and how to resolve it?