Question : Getting a "postbacktrigger is not a known element" ASP.NET waring

I get a "postbacktrigger is not a known element" warning within the following AJAX update panel. Any ideas on what I'm missing?

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                    <asp:UpdatePanel id="uPnlC_Step42_UploadRules" runat="server">
                    <contenttemplate>
                        <asp:Button ID="btn_Step42_UploadRules" runat="server" BackColor="#4066B3" BorderColor="White"
                            BorderStyle="Solid" BorderWidth="1px" Font-Bold="True" ForeColor="White" Height="25px"
                            Text="Upload" Width="175px" OnClick="btn_Step42_UploadRules_Click" />
                        <triggers>
                            <asp:PostBackTrigger ControlID="btn_Step42_UploadRules" />                
                        </triggers>

                    </contenttemplate>
                    </asp:UpdatePanel>

Answer : Getting a "postbacktrigger is not a known element" ASP.NET waring

Try putting the triggers tag outside content template

<asp:UpdatePanel id="uPnlC_Step42_UploadRules" runat="server">
<contenttemplate>
<asp:Button ID="btn_Step42_UploadRules" runat="server" BackColor="#4066B3" BorderColor="White"
BorderStyle="Solid" BorderWidth="1px" Font-Bold="True" ForeColor="White" Height="25px"
Text="Upload" Width="175px" OnClick="btn_Step42_UploadRules_Click" />

</contenttemplate>
<triggers>
<asp:PostBackTrigger ControlID="btn_Step42_UploadRules" />
</triggers>
</asp:UpdatePanel>