ASP.NET Error:The state information is invalid for this page and might be corrupted

I have no JQuery or other javascript changing values or html-structure. And I have no controls that is added dynamically.

Still I get the error: The state information is invalid for this page and might be corrupted

The error occurs somewhat random. Here is how I can replicate the issue, aspx-file:

<%@ Page ViewStateEncryptionMode ="Never" MaxPageStateFieldLength="40" ValidateRequest="false" Language="C#" AutoEventWireup="true" EnableEventValidation="false" CodeFile="tbTest.aspx.cs" Inherits="_Default" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <title>tbTest </title>
</head>
<body>
    <form id="form1" runat="server">
    <asp:Button id="Submit1" type="submit"  
        runat="server" onClick="btnclick_Click" Text="Submit" /><br />
    <asp:TextBox ID="tbStatus" enableViewState="true" runat="server" TextMode="MultiLine" 
        Width="617px" Height="67px" ReadOnly="True" Font-Size="Smaller"></asp:TextBox>
    <br />
   </form>
</body>
</html>

.cs-file:

public partial class _Default : System.Web.UI.Page 
{
    protected void Page_Init(object sender, EventArgs e)
    {
        if (!Page.IsPostBack)
        {
            DateTime timestamp = DateTime.Now;
            try
            {
                tbStatus.Text = timestamp.ToString() + ". Page Loaded. ";
            }catch (Exception ex) {
            }
        }
    }

    protected void Page_Load(object sender, EventArgs e)
    {
        if (!Page.IsPostBack)
        {
            try
            {
                Response.Cache.SetNoStore();
            } catch (Exception ex){
            } 
        }    
    }

    protected void btnclick_Click(object sender, EventArgs e)
    {
        DateTime timestamp = DateTime.Now;
        try
        {
            tbStatus.Text += Environment.NewLine + timestamp.ToString() + ". TextBox updated. ";

        } catch (Exception ex) {
            tbStatus.Text += Environment.NewLine + timestamp.ToString() + ". Error. " + ex.Message.ToString();
        }
    }
}

This really gives me head-ache. After 3-4 submits the error is there. I have tested changing values for ViewStateEncryptionMode, MaxPageStateFieldLength, ValidateRequest, AutoEventWireup and EnableEventValidation without success.

What can be wrong?

Solution

Just set the enableEventValidation attribute in the web.config file for the asp.net application to false.

might also need to check http://blog.syedgakbar.com/2007/11/one-possible-reason-for-the-state-information-is-invalid-for-this-page-exception/

And

http://support.microsoft.com/default.aspx?scid=kb;EN-US;829743

IIS compression enabled on IIS6 can also cause this. Verify this is turned off.