Server Error in '/' Application.

Value cannot be null.
Parameter name: String

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.ArgumentNullException: Value cannot be null.
Parameter name: String

Source Error:


Line 32:         soTrangMacDinh = 20;
Line 33:         sp = new BusiSanPham();
Line 34: 		sanPham.MaNhomSanPham = int.Parse(Request.QueryString["id"]);
Line 35: 		var a = sp.xuatten(sanPham);
Line 36: 		if(Request.QueryString["id"] == "10")

Source File: d:\inetpub\vhosts\nhadatphanthiet.vn\httpdocs\vi\du-an.aspx.cs    Line: 34

Stack Trace:


[ArgumentNullException: Value cannot be null.
Parameter name: String]
   System.Number.StringToNumber(String str, NumberStyles options, NumberBuffer& number, NumberFormatInfo info, Boolean parseDecimal) +7487514
   System.Number.ParseInt32(String s, NumberStyles style, NumberFormatInfo info) +119
   System.Int32.Parse(String s) +23
   vi_du_an.Page_Load(Object sender, EventArgs e) in d:\inetpub\vhosts\nhadatphanthiet.vn\httpdocs\vi\du-an.aspx.cs:34
   System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) +14
   System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +35
   System.Web.UI.Control.OnLoad(EventArgs e) +99
   System.Web.UI.Control.LoadRecursive() +50
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +627


Version Information: Microsoft .NET Framework Version:2.0.50727.8964; ASP.NET Version:2.0.50727.8962