In this tutorial i will let you know how to auto refresh or update GridView using AJAX Timer and UpdatePanel in asp.net. In this it is described that how a GridView is update after a specific time set in timer control.
public partial class _Default : System.Web.UI.Page
protected void Page_Load(object sender, EventArgs e)
protected void Timer1_Tick(object sender, EventArgs e)
update.Text = " Gridview Was Last Updated at " + DateTime.Now;
public void databind()
string strcon = ConfigurationManager.ConnectionStrings["con"].ConnectionString;
SqlConnection conn = new SqlConnection(strcon);
string str = "select * from dept";
SqlCommand cmd = new SqlCommand(str, conn);
SqlDataAdapter da = new SqlDataAdapter(cmd);
DataTable dt = new DataTable();
GridView1.DataSource = dt;
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I am getting the below error in my ASP.NET 4.0 web application:
Validation of viewstate MAC failed. If this application is hosted by a Web Farm or cluster, ensure that <machineKey> configuration specifies the same validationKey and validation algorithm. AutoGenerate cannot be used in a cluster.
I started getting this error when I added the below tag in web.config to encrypt the viewstate:
I looked for lot of solutions on aspnet forums and Internet but nothing worked. If I change the viewStateEncryptionMode to "Auto" or "Never", then the page loads fine. But that would make my application insecure and security is my prime objective.
FYI:My application is deployed on a Windows 2008 R2 server and not on a webfarm.
Any solution to solve this issue?
First, just to check the simplest solution, you aren't posting back "old" pages are you? By this I mean getting the page when the viewstateEncryptionMode is off/auto, switching the mode to on then posting back. This wide cause the error, but is unlikely Tokyo are doing this.
This problem is ringing a bell, but I can't place my finger on it. You might be suffering from this http://blogs.msdn.com/b/tom/archive/2008/03/14/validation-of-viewstate-mac-failed-error.aspx (On my mobile so can't make clickety),though this was fixed IIRC.