ASP.NET - Session Object reference not set to an instance of an object

 Hi!I have 2 type of registration one is customer another one is consultant,If someone is loggin but he has register as a customer means if he tried to click on a link of consultant,the system should tell him that is not a consultant as shown in the code bellow:This is a generic handler I have created to avoid that.But I am getting this error:<<Object reference not set to an instance of an object>>

 public void ProcessRequest (HttpContext context) {
        if (HttpContext.Current.Session["UserId"] != null)
        {
            ProductInfo _ProductInfo = new ProductInfo();
            _ProductInfo.UserId = Convert.ToInt32(HttpContext.Current.Session["UserId"]);
            var _ProductList = _ProductInfo.GetServiceByUserId();
            var serializer = new System.Web.Script.Serialization.JavaScriptSerializer();
            HelperFunctions.InitializeCulture();
            var result = new
            {
                iTotalRecords = _ProductList.Count(),
                iTotalDisplayRecords = _ProductList.Count(),
                aaData = _ProductList.Select(p => new object[] { p.SN, p.ProductName, p.CategoryName, string.Format("<a href=\"#\" title=\"{0}\" class=\"product-view\">{0}<a>|{2}<a href=\"#\" title=\"{1}\" class=\"delete-icon product-delete\">{1}</a>", Resources.Language.View, Resources.Language.Delete, !p.Approved ? string.Format("<a href=\"#\" title=\"{0}\" class=\"product-edit\">{0}</a>|", Resources.Language.Edit) : string.Empty), p.ProductId })
            };
            var json = serializer.Serialize(result);
            context.Response.ContentType = "text/plain";
            context.Response.Write(json);
        }
        else {
            context.Response.Write(false);
            context.Response.Write("You are not register as a consultant to view the service page.</br>");
             
        }
            
    }

and the GetServiceByUserId() method is defined like this,if need to know what is returning:

 public IEnumerable<ProductInfo> GetServiceByUserId()
    {
        using (SqlDataReader sdr = SqlHelper.ExecuteReader(SqlHelper.GetConnection(), "GetServiceByUserId", UserId))
        {
            if (sdr.HasRows)
            {
                 
                while (sdr.Read())
                { 
                    yield return new ProductInfo
                    {
                        SN = Convert.ToInt32(sdr["SN"]),
                        ProductId = Convert.ToInt32(sdr["ProductId"]),
                        ProductName = Convert.ToString(sdr["ProductName"]),
                        CategoryName = Convert.ToString(sdr["CategoryName"]),
                        Approved = Convert.ToBoolean(sdr["Approved"])
                    };
                }
            }
        }
    }

can help fixing this issue.
 

Use the "context" passed into the ProcessRequest handler not the main one you are using now.

 if (context.Session["UserId"] != null)

Hi Morris!It is giving me the error.I have changed like u said:
 public void ProcessRequest (HttpContext context) {
        if (context.Session["UserId"] != null)
        {
            ProductInfo _ProductInfo = new ProductInfo();
            _ProductInfo.UserId = Convert.ToInt32(HttpContext.Current.Session["UserId"]);
            var _ProductList = _ProductInfo.GetServiceByUserId();
            var serializer = new System.Web.Script.Serialization.JavaScriptSerializer();
            HelperFunctions.InitializeCulture();
            var result = new
            {
                iTotalRecords = _ProductList.Count(),
                iTotalDisplayRecords = _ProductList.Count(),
                aaData = _ProductList.Select(p => new object[] { p.SN, p.ProductName, p.CategoryName, string.Format("<a href=\"#\" title=\"{0}\" class=\"product-view\">{0}<a>|{2}<a href=\"#\" title=\"{1}\" class=\"delete-icon product-delete\">{1}</a>", Resources.Language.View, Resources.Language.Delete, !p.Approved ? string.Format("<a href=\"#\" title=\"{0}\" class=\"product-edit\">{0}</a>|", Resources.Language.Edit) : string.Empty), p.ProductId })
            };
            var json = serializer.Serialize(result);
            context.Response.ContentType = "text/plain";
            context.Response.Write(json);
        }
        else {
            context.Response.Write(false);
            context.Response.Write("You are not register as a consultant to view the service page.</br>");
             
        }
            
    }

Gotta change it here too:

 _ProductInfo.UserId = Convert.ToInt32(HttpContext.Current.Session["UserId"]);

For future reference, it is helpful if you post what line the error occurs on.

Morris!I got the same problem.This the code 

Ah, then you probably are not implementing the proper interface for Session in your http handler:

public MyHttpHandlerClass : IHttpHandler, IRequiresSessionState

Thanks Morris!