and error : The underlying provider failed on Open.

public static IEnumerable<tbl_index_menu> PutParentInMenuTop()
        {
            using (SportContext db = new SportContext())
            {
                return db.tbl_index_menu.Where(z => z.parent == 0 && z.id_position == 1 &&    z.name_menu != "home").OrderBy(z => z.orderlist).ToList();
            }
        }