How to make UpdatePanel to do Update after custom Event? - asp.net

Question

I'm setting UpdatePanel1.UpdateMode = UpdatePanelUpdateMode.Conditional; to make manual updates but it doesn't work for some custom events, when I have some event alike here:
protected void Button1_Click(object sender, EventArgs e) {
discovery.FindAlreadyRegisteredServices();
discovery.discoveryClient.FindCompleted += FoundEvent;
protected void FoundEvent(object sender, FindCompletedEventArgs e) {
Label1.Text = (discovery.endpoints.Count > 0) ? discovery.endpoints[0].Address.ToString() : "nothing";
UpdatePanel1.Update();
}
My project is failing with:
An unhandled exception of type 'System.InvalidOperationException' occurred in System.ServiceModel.Internals.dll
Additional information: The Update method can only be called on UpdatePanel with ID 'UpdatePanel1' before Render.
even if I set ChildrenAsTriggers or not. Error message is not clear for me and I can't understand what should I do to process update right after I process my event?
addition:
aspx:
<asp:UpdatePanel ID="UpdatePanel1" UpdateMode="Conditional" runat="server">
<ContentTemplate>
<asp:Button ID="Button1" runat="server" Text="Button" onclick="Button1_Click" />
<asp:Label ID="Label1" runat="server" Text=""></asp:Label>
<asp:ListView ID="ListView1" runat="server">
</asp:ListView>
</ContentTemplate>
</asp:UpdatePanel>

Answer 1

I suppose you should change your markup like this
<asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Conditional">
....
You should set UpdateMode="Conditional" in your markup itself

Answer 2

protected void Button1_Click(object sender, EventArgs e) {
discovery.FindAlreadyRegisteredServices();
discovery.discoveryClient.FindCompleted += FoundEvent;
// Try to call the update method after calling the custom even but in the click event of the button. Ensure you update the Trigger accordingly in the update panel
**UpdatePanel1.Update();**
}
protected void FoundEvent(object sender, FindCompletedEventArgs e) {
Label1.Text = (discovery.endpoints.Count > 0) ? discovery.endpoints[0].Address.ToString() : "nothing";
}
Try to add AsyncPostBackTrigger to the update panel with update mode as conditional
Although you are doing same thing explicitly.
<Triggers>
<asp:AsyncPostBackTrigger ControlID="Button1" EventName="Click" />
</Triggers>
Just to check if there is any other issue, you can set the updateMode property of the update panel to "Always"