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update panel - dropdown selected index change event not triggering

I have one dropdownlist on my page (.aspx) and based on change of selected value i need to bind the data to checkboxlist control which is on the same page. To avoid entire page to be refreshed, i have put the controls in the update panel.
But when i am changes the selection from the dropdown,, it is getting back to the first value itself and the selected index changed even is not getting triggered.
here is how I have put my controls in the update panel.
<asp:Content ID="Main" ContentPlaceHolderID="PlaceHolderMain" runat="server">
<asp:ScriptManagerProxy ID="ScriptManagerProxy1" runat="server"></asp:ScriptManagerProxy>
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>
<fieldset>
<div id="attachmentdiv">
<asp:DropDownList ID="ddlimportfiles" runat="server" AutoPostBack="true" OnSelectedIndexChanged="ddlimportfiles_onselectedindexChange"></asp:DropDownList>
</div>
<div id="voltagediv">
<asp:CheckBoxList ID="chkBoxLstVoltage" runat="server"></asp:CheckBoxList>
</div>
<asp:Button ID="btnGenerateZBF" runat="server" Text="Generate ZBF" OnClick="GenerateZBF_Click" />
</fieldset>
</ContentTemplate>
<Triggers>
<asp:AsyncPostBackTrigger ControlID="ddlimportfiles" EventName="SelectedIndexChanged" />
</Triggers>
</asp:UpdatePanel>
</asp:Content>
kindly suggest what I am doing wrong here.

Update panel not working in two asp panel

In my ascx page I have two panel,I trying to change these panels inside an update panel.but the page load is going on each click on radio button.here is my code
<asp:ScriptManager ID="ScriptManager1" runat="server">
</asp:ScriptManager>
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>
<asp:Panel ID="Panel2" runat="server" >
<asp:RadioButtonList runat="server" ID="radioListAnswers" RepeatDirection="Horizontal" AutoPostBack="true" ClientIDMode="Static" onselectedindexchanged="radioListAnswers_SelectedIndexChanged">
</asp:RadioButtonList>
</asp:Panel>
</ContentTemplate>
</asp:UpdatePanel>
<asp:UpdatePanel ID="UpdatePanel2" runat="server">
<Triggers>
<asp:AsyncPostBackTrigger ControlID="radioListAnswers" EventName="SelectedIndexChanged"/>
</Triggers>
<ContentTemplate>
<asp:Panel ID="Panel1" runat="server" Visible="false">
<div> Thanks</div>
</asp:Panel>
</ContentTemplate>
</asp:UpdatePanel>
here is my code behind
void radioListAnswers_SelectedIndexChanged(object sender, EventArgs e)
{
panel2.Visible=false;
panel1.Visible=true;
}
on click on each radio button the page is reloading.How can we over come this.
Thanks in advance for help.

i hope this will help. Pls check this link
https://msdn.microsoft.com/en-us/library/bb398867(v=vs.140).aspx

ASP.NET Update Panel within ListView Control not updating

Basically I have this situation
Page >
Update Panel >
User Control >
List View >
User Control (Within item template) >
Update Panel
When I click on a button within the inner most update panel, I want the content of the update panel to update. This isn't happening. However, the click handler is being hit fine asynchronously. The update panel just doesn't want to update.
Code - I've created a simple test web app that replicates the problem, and shared it on my google drive: UpdatePanelInListViewTest.zip, but here's the markup:
Page:
<asp:ScriptManager ID="ScriptManager1" runat="server">
</asp:ScriptManager>
<asp:UpdatePanel ID="ajaxParent" runat="server" UpdateMode="Conditional">
<ContentTemplate>
<uc1:ListUserControl ID="ListUserControl1" runat="server" />
</ContentTemplate>
</asp:UpdatePanel>
List User Control:
<%# Control Language="C#" AutoEventWireup="true" CodeBehind="ListUserControl.ascx.cs" Inherits="UpdatePanelInListViewTest.ListUserControl" %>
<%# Register src="MiniWidget.ascx" tagname="MiniWidget" tagprefix="uc1" %>
<asp:ListView ID="lstTest" runat="server">
<ItemTemplate>
Item
<uc1:MiniWidget ID="MiniWidget1" runat="server" />
</ItemTemplate>
</asp:ListView>
Mini Widget User Control
<%# Control Language="C#" AutoEventWireup="true" CodeBehind="MiniWidget.ascx.cs" Inherits="UpdatePanelInListViewTest.MiniWidget" %>
<asp:UpdatePanel ID="ajaxWidget" runat="server" UpdateMode="Conditional">
<ContentTemplate>
<asp:LinkButton ID="lnkTest" runat="server" onclick="lnkTest_Click">Test</asp:LinkButton>
<asp:Label ID="lblTest" runat="server" Text=""></asp:Label>
</ContentTemplate>
</asp:UpdatePanel>
I've tried different permutations of this; i.e. having the button outside the panel and adding a trigger etc but I just cannot get it to update.
It appears that because the user control is within an item template of the parent list view it causes the update panel to not update for some reason...

The problem is to do with when you call the databind method within ListUserControl.
Moving lstTest.DataBind(); so that it executes within the Page_Load rather than the Page_PreRender fixes the issue for your simple test web app.

have u tried:
<asp:UpdatePanel ID="ajaxPanel" runat="server" ChildrenAsTriggers="true" UpdateMode="Conditional">
<Triggers>
<asp:AsyncPostBackTrigger ControlID="btnTest" />
</Triggers>
<ContentTemplate>
<asp:Label ID="Label1" runat="server" Text="Label"></asp:Label>
<asp:Button ID="btnTest" runat="server" Text="Test" onclick="btnTest_Click" />
</ContentTemplate>
</asp:UpdatePanel>

AJAX In ItemTemplate Doesn't Work

In this aspx code example the Timer inside UpdatePanel in ListView doesn't make async refresh. In this code it refreshes the whole page like AJAX doesn't exists here. What should I do to remove this problem ?
<form id="form1" runat="server">
<div>
<asp:ScriptManager ID="ScriptManager1" runat="server"></asp:ScriptManager>
<asp:Label ID="Label1" runat="server" Text="SIMPLE FIELD"></asp:Label>
<br />
<asp:ListView ID="DataListView" runat="server">
<ItemTemplate>
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>
<asp:Timer ID="Timer1" runat="server" Interval="500"></asp:Timer>
<asp:Label ID="Label2" runat="server" Text="AJAX"></asp:Label>
</ContentTemplate>
</asp:UpdatePanel>
</ItemTemplate>
</asp:ListView>
</div>
</form>

You should wrap the entire ListView in the UpdatePanel.
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>
<asp:ListView ID="DataListView" runat="server">
<ItemTemplate>
<asp:Timer ID="Timer1" runat="server" Interval="500"></asp:Timer>
<asp:Label ID="Label2" runat="server" Text="AJAX"></asp:Label>
</ItemTemplate>
</asp:ListView>
</ContentTemplate>
</asp:UpdatePanel>

I think there might be an issue where because the ListView doesn't do any rendering of its own, the UpdatePanel can't figure out the "parent" item to update. I think it's an unfortunate consequence of the design of the UpdatePanel.
I would recommend trying to put the UpdatePanel inside its own container control, such as an and see if that produces the correct result.

Create Loading animation before navigating to another page and disable all conrols on it during animation

I have a button on Page 1 and when the button click event occurs, I had to do some process that takes around 2-3 seconds. So, I want to Put a Loading Image in Center and disable all other controls on the Page 1.
I tried using UpdatePanel :
<asp:ScriptManager ID="ScriptManager1" runat="server">
</asp:ScriptManager>
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>
<asp:Button runat="server" Text="Button" onclick="Unnamed1_Click" />
<asp:Label runat="server" Text="Label" ID="lbl"></asp:Label>
</ContentTemplate>
</asp:UpdatePanel>
<asp:UpdateProgress ID="UpdateProgress1" runat="server" AssociatedUpdatePanelID="UpdatePanel1" >
<ProgressTemplate>
<div id="IMGDIV1" align="center" valign="middle" runat="server" style="position: absolute;visibility:visible;vertical-align:middle;border-style:none;border-color:black;background-color:transparent;">
<asp:Image ID="Image1" runat="server" ImageUrl="~/ajax-loader (1).gif" />
</div>
</ProgressTemplate>
</asp:UpdateProgress>
But the controls did not get disabled. Any Solution or Javascript ??
Also I want that it should work if want to stay on the same page.

why dont yu use telerik radgrid loading panel ?
http://www.telerik.com/help/aspnet-ajax/ajax-center-loadingpanel.html