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

[idwaikat]

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 Object, ByVal 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???

[Veselin Vasilev]

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 Object, ByVal 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 .]

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

[Simon]

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