会话名称在当前上下文中不存在

Question

我正在尝试在会话中存储登录用户的信息。但是，它似乎在我的应用程序中不起作用。我不断收到错误消息“当前上下文中不存在名称'Session'”

  [HttpPost]
    public ActionResult userLogin(User user)
    {
        using (TheDbContext db = new TheDbContext())
        {
            var usr = db.userAccount.Single(u => u.Email == user.Email && u.Password == user.Password);

            if (usr != null)
            {

                Session["UserID"] = usr.ID.ToString();
                Session["Email"] = usr.Email.ToString();

                return RedirectToAction("LoggedIn");
            }

        }
            return View();
    }