Hey, I’ve dealt with this exact frustrating issue before when working with ASP.NET UpdatePanels and TabControls. The problem usually boils down to event binding getting lost after an async postback, or controls not being properly tracked in ViewState. Let’s go through the most likely fixes step by step:

1. Ensure Your LinkButtons Are Properly Wrapped in the UpdatePanel #

Looking at your code snippet, your panelKayit starts hidden—first, double-check that LinkButton5 and LinkButton6 are actually inside that panel, and that the entire TabControl (and its TabPanels) are within the UpdatePanel’s ContentTemplate. If the TabControl lives outside the UpdatePanel, async postbacks can mess up the tab’s state and break control events.

Here’s a corrected structure example:

<asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Conditional">
    <ContentTemplate>
        <!-- Make sure your TabControl is inside the UpdatePanel -->
        <asp:TabControl ID="TabControl1" runat="server" OnSelectedIndexChanged="TabControl1_SelectedIndexChanged">
            <asp:TabPanel ID="TabPanel1" runat="server" HeaderText="Kayit">
                <ContentTemplate>
                    <asp:Panel ID="panelKayit" runat="server" Visible="false">
                        <asp:LinkButton ID="LinkButton5" runat="server" Text="Hesapla" OnClick="LinkButton5_Click" />
                        <asp:LinkButton ID="LinkButton6" runat="server" Text="Kaydet" OnClick="LinkButton6_Click" />
                    </asp:Panel>
                </ContentTemplate>
            </asp:TabPanel>
        </asp:TabControl>
    </ContentTemplate>
    <Triggers>
        <asp:AsyncPostBackTrigger ControlID="LinkButton5" EventName="Click" />
        <asp:AsyncPostBackTrigger ControlID="LinkButton6" EventName="Click" />
        <!-- Add this if your TabControl's index change needs to be async too -->
        <asp:AsyncPostBackTrigger ControlID="TabControl1" EventName="SelectedIndexChanged" />
    </Triggers>
</asp:UpdatePanel>

2. Maintain Visibility State on Every Postback #

Since panelKayit starts hidden, you need to explicitly set its Visible property on every postback (including async ones). If you don’t, after the first async postback that shows it, the next postback might reset it to hidden (or lose track of its state), breaking the buttons.

Add this to your code-behind:

protected void Page_Load(object sender, EventArgs e)
{
    // Adjust this condition to match when you want the panel visible
    if (TabControl1.SelectedIndex == 0) // Example: show when first tab is active
    {
        panelKayit.Visible = true;
    }
}

3. Manually Register Async Postback Controls #

Sometimes, when controls are nested inside a NamingContainer (like a TabPanel), the UpdatePanel’s triggers can’t find them correctly. Fix this by registering the LinkButtons directly with the ScriptManager in the Page_Init event:

protected void Page_Init(object sender, EventArgs e)
{
    ScriptManager scriptManager = ScriptManager.GetCurrent(this);
    scriptManager.RegisterAsyncPostBackControl(LinkButton5);
    scriptManager.RegisterAsyncPostBackControl(LinkButton6);
}

4. Tweak UpdatePanel Settings #

Try adjusting the UpdatePanel’s UpdateMode and ChildrenAsTriggers properties. Setting ChildrenAsTriggers="true" ensures child controls trigger updates, and UpdateMode="Conditional" keeps things efficient (you can also try Always temporarily to test):

<asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Conditional" ChildrenAsTriggers="true">

5. Check for Dynamic Controls (If Applicable) #

If you’re creating the LinkButtons dynamically instead of declaratively, you must recreate them and rebind their click events in the Page_Init or Page_Load event every time the page loads. Async postbacks rebuild the control tree, so missing this step means the event handlers won’t be attached.

内容的提问来源于stack exchange，提问作者Sebnem Demircioglu