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Server.Transfer/Response.Redirect cannot be called in a page callback

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ComboBox
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idwaikat
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idwaikat asked on 06 Jul 2009, 12:46 PM
Hi all

I have a combobox as follows:


<telerik:RadComboBox ID="cmbobox" runat="server" AutoPostBack="true" EnableLoadOnDemand="true"></telerik:RadComboBox> 


Also I have the vb code:


Protected Sub cmbobox_ItemsRequested(ByVal o As ObjectByVal e As Telerik.Web.UI.RadComboBoxItemsRequestedEventArgs) Handles cmbobox.ItemsRequested 
  
        Dim objDataBaseClass As New DataBaseClass() 
        Dim dtDatabase As DataTable = objDataBaseClass.GetSomedataById(e.Text) 
  
        If dtDatabase Is Nothing Then 'or any other condition that checks for errors 
        'Here I need to go to error page: 
        'Response.Redirect("~/ErrorPage.aspx") 
        'Server.Transfer("~/ErrorPage.aspx") 
        End If 
  
        cmbobox.Items.Add(New RadComboBoxItem("""")) 
        For i As Integer = 0 To dtDatabase .Rows.Count - 1 
            cmbobox.Items.Add(New RadComboBoxItem(dtDatabase .Rows(i)("ID").ToString() & " - " & dtDatabase .Rows(i)("NAME").ToString(), dtDatabase.Rows(i)("ID").ToString())) 
        Next 
    End Sub 



The problem is on lines (8 & 9), I am trying to go to another page to display some information about the error, but an exception thrown:

Server.Transfer cannot be called in a page callback

or

Response.Redirect cannot be called in a Page callback

I tired to register some client script like window.location but it does not work.

Please can you give me some help???




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Veselin Vasilev
Telerik team
answered on 09 Jul 2009, 09:42 AM
Hello idwaikat,

You can throw new application exception in ItemsRequested event and subscribe to the OnClientRequestFailed event and redirect there:

Protected Sub RadComboBox1_ItemsRequested(ByVal o As ObjectByVal e As RadComboBoxItemsRequestedEventArgs) Handles RadComboBox1.ItemsRequested         
        Throw New ApplicationException() 
    End Sub 

<telerik:RadComboBox ID="RadComboBox1" runat="server"  
    OnClientItemsRequestFailed="onRequestFailed" 
    EnableLoadOnDemand="true"
</telerik:RadComboBox> 
<script type="text/javascript"
    function onRequestFailed(sender, e) { 
        e.set_cancel(true); 
        document.location.href = "ErrorPage.aspx"
    } 
</script>  


Best wishes,
Veselin Vasilev
the Telerik team

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Awadh .
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answered on 09 Jul 2010, 12:23 PM
Hi Veselin,

I am also facing similar problem, But my question is why this happening means root cause & why with rad controls ? Why not with regular .Net controls ?

Because in my case, similar code was working fine earlier, but now giving same error whenever application tries to redirect to the error page.


Thanks,
Awadh
0
Simon
Telerik team
answered on 09 Jul 2010, 01:00 PM
Hello Awadh .,

This is a generic error which lies in the ASP.NET Framework itself - Redirect of a page cannot happen while in an AJAX callback.

Please see this thread for more info.

Kind regards,
Simon
the Telerik team
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ComboBox
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idwaikat
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Answers by
Veselin Vasilev
Telerik team
Awadh .
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Simon
Telerik team
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