Hi

My goal is when a user selects a language from a dropdown list the page will then be redirected to another master page.

I have gone so far but get the following error.

"Object reference not set to an instance of an object"

Please can someone help? feel free to change my code as needed

<%@ Page Title="" Language="VB" MasterPageFile="~/nwp_test.master" AutoEventWireup="false" CodeFile="Test_master.aspx.vb" Inherits="Test_master" %>

<asp:Content ID="Content1" ContentPlaceHolderID="head" Runat="Server">
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder2" Runat="Server">
 
</asp:Content>
<asp:Content ID="Content3" ContentPlaceHolderID="ContentPlaceHolder1" Runat="Server">
<asp:Label ID="Label1" runat="server" meta:resourceKey="Label1"></asp:Label>
        
      
        <br />
        <br />
        
        <asp:Label ID="Welcome" runat="server"
            Text="<%$ Resources:Resource, Welcome %>"></asp:Label>
        <br />
        <br />
        <asp:DropDownList ID="language1" runat="server" AutoPostBack="True">
            <asp:ListItem Value="en-gb">english</asp:ListItem>
             <asp:ListItem Value="fr">French</asp:ListItem>
              <asp:ListItem Value="cy-gb">Cymraeg</asp:ListItem>
           
        </asp:DropDownList>

    <br />
    <br />
    <asp:Label ID="Label2" runat="server" Text="Label"></asp:Label>
</asp:Content>

Imports System.Threading
Imports System.Globalization

Partial Class Test_master
    Inherits Page

    Protected Overrides Sub InitializeCulture()
        Dim lang As String = Request("language1")

        If lang IsNot Nothing Or lang <> "" Then
            Thread.CurrentThread.CurrentUICulture = New CultureInfo(lang)
            Thread.CurrentThread.CurrentCulture = CultureInfo.CreateSpecificCulture(lang)
        End If
    End Sub

   

    Public Sub Page_PreInit(ByVal sender As Object, _
    ByVal e As EventArgs) Handles Me.PreInit
        If language1.SelectedValue = "cy-gb" Then
            Label2.Text = "bonjour"
        End If
        Me.MasterPageFile = "~/cy/nwp_cy.master"
    End Sub

   
End Class

You are trying to do it on Page_PreInit, so you need to do it like this

if ((Request.Form["language1"] != null))

        {

            String selectedLanguage = Request.Form["language1"];

if(selectedLanguage.Equels("cy-gb"))

{

/*Change label text */

}

else

{

/*Change master page file*/

}

Still baffeld!

What is the error, object refrence is null? or master page is not changed? Can you debug and see on which line it occured?

I suspect it could also come on 

Label2.Text = "bonjour"

Try to do above setting later inseted , may be on page load.

else refer this:

http://blog.tatham.oddie.com.au/2008/12/20/accessing-aspnet-page-controls-during-preinit/