[Solved] ASP.Net Core Session Error: Cannot implicitly convert type string to system.datetime

I am having this error inside my [httpget] controller

usr.LastLoggedDate = HttpContext.Session.GetString("logg"));

cannot implicitly convert type string to system.datetime

I declared the http context set session inside the login controller

var dt = LastLoggedDate.ToString("MM/dd/yyyy");
HttpContext.Session.SetString("Logg", dt);
usr.LastLoggedDate = LastLoggedDate;

MY CODE

namespace Feed100.Controllers
{
    public class UserDetailController : Controller
    {
        //UserDetailDataManagement objBL = new UserDetailDataManagement();
        UserDetailDataManagement objBL = new UserDetailDataManagement();
        public ActionResult Index()
        {

            return View();
        }

        [HttpGet]
        public IActionResult Create()
        {
            UserDetail usr = new UserDetail();

            // Get Session value.
            usr.CreatedBy = HttpContext.Session.GetString("CurrUSerID");

            usr.LastLoggedDate = HttpContext.Session.GetString("logg"));
            if (usr.CreatedBy != null)
            {
                ViewBag.Info = usr.CreatedBy;
                ViewBag.Enfo = usr.LastLoggedDate;
                return View();
            }
            else
            {
                return RedirectToAction("Login");
            }
            return View();
        }

        public IActionResult Login()
        {
            return View();
        }
        [HttpPost]
        public IActionResult login(string userID, string password, DateTime LastLoggedDate)
        {
            UserDetail usr = new UserDetail();
            // Get Session value.
            // usr.CreatedBy = HttpContext.Session.SetString("CurrUSerID", usr.UserID);
            if (!ModelState.IsValid)
            {
                return View();
            }
            UserDetail erp = objBL.GetLogin(userID, password);
            if (erp != null)
            {
                HttpContext.Session.SetString("CurrUSerID", userID);
                usr.UserID = userID;
                var dt = LastLoggedDate.ToString("MM/dd/yyyy");
                HttpContext.Session.SetString("Logg", dt);
                usr.LastLoggedDate = LastLoggedDate;
                return RedirectToAction("Create");
            }
            else
                // Invalid UserId Or Password.
                ViewBag.Error = "Login failed";
            return View();
        }
    }
}

PLEASE HELP ME

namespace DLFeed100.Model
{
    [Table("UserDetails")]
    public class UserDetail
    {
        [Key]
        public string UserID { get; set; }
        public string Password { get; set; }
        public string Name { get; set; }
        public Int64 MobNumber { get; set; }
        public string EmailID { get; set; }
        public string EmpID { get; set; }
        public string RoleID { get; set; }
        public string DesignID { get; set; }
        public DateTime? LastLoggedDate { get; set; }
        public string CreatedBy { get; set; }           
    }
}