Microsoft KB Archive/316920

= PRB: &quot;View State Is Invalid&quot; Error Message When You Use Server.Transfer =

Article ID: 316920

Article Last Modified on 4/19/2007

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APPLIES TO


 * Microsoft ASP.NET 1.0

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This article was previously published under Q316920



SYMPTOMS
When you use HttpServerUtility.Transfer(&quot; &quot;, true), you receive the following error message:

The View State is invalid for this page and might be corrupted



CAUSE
This problem occurs because the EnableViewStateMac attribute of the   element is set to true by default. When this attribute is set to true, ASP.NET runs a message authentication check (MAC) on the view state of the page when the page is posted back from the client. This check determines if the view state of the page was modified on the client. For security purposes, it is recommended that you keep this attribute set to true.

When you call the Server.Transfer method and set the second parameter to true, you preserve the QueryString and the Form collections. One of the form fields is the hidden __VIEWSTATE form field, which holds the view state for the page. The view state message authentication check fails because the message authentication check only checks each page. Therefore, the view state from the page that calls Server.Transfer is not valid on the destination page.

View state is page scoped and is valid for that page only. View state should not be transferred across pages.



RESOLUTION
To resolve this problem, use one of the following methods.

Resolution 1
Transfer values between pages to pass your server control values to the other pages. For more information, refer to the following MSDN documentation:

Passing Server Control Values Between Pages

http://msdn2.microsoft.com/en-us/library/6c3yckfw(vs.71).aspx

This requires that you create public properties for each property of a control that you want to access from the destination page.

If you have many controls, and if you want to access the properties of these controls from another page, you can also declare those controls as public variables. For example:

Page1.aspx Public Class Page1 Public WithEvents TextBox1 As System.Web.UI.WebControls.TextBox

'Insert your code here. End Class Page2.aspx Dim sourcePage As Page1 sourcePage = CType(Context.Handler, WebForm1) Response.Write(sourcePage.TextBox1.Text)

Resolution 2
Do not pass the second parameter (which is false by default) when you call Server.Transfer. For example: Server.Transfer(&quot; &quot;) This code does not send the QueryString and the Form fields to the page that is called. When no data is transferred, ASP.NET does not run the message authentication check.



Steps to Reproduce the Behavior
  Create an .aspx page named WebForm1.aspx that transfers execution to another page. Add the following code to WebForm1.aspx: <%@ Page language=&quot;vb&quot; AutoEventWireup=&quot;true&quot; %>

 Your Name 

Sub Button1_Click(sender As Object, e As System.EventArgs) Server.Transfer(&quot;WebForm2.aspx&quot;,true) End Sub

  Create another .aspx page named WebForm2.aspx, and then add the following code: <%@ Page language=&quot;vb&quot; AutoEventWireup=&quot;true&quot; %>

 Web Form 2</asp:Label>

Sub Page_Load(sender As Object, e As EventArgs)

Dim thisPage As System.Web.UI.Page Dim nameTextBox As TextBox

thisPage = CType(Context.Handler, System.Web.UI.Page) nameTextBox = CType(thisPage.FindControl(&quot;txtName&quot;), System.Web.UI.Control)

lblName.Text = &quot;Your name is '&quot; & nameTextBox.Text & &quot;'.&quot; End Sub

</li> Open WebForm1.aspx in your browser, and then click Submit.</li></ol>

Additional query words: ViewState

Keywords: kbprb kbstate kbwebforms KB316920

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