I try to make a date picker using ImageButton and calender, to avoid screen flicker I used ajax update panel control, but some errors appear, it said "The control with ID 'UpdatePanel1' requires a ScriptManager on the page. The ScriptManager must appear before any controls that need it."
Here is my code
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>
<asp:Calendar CssClass="form-control" ID="Calendar1" runat="server" OnSelectionChanged="Calendar1_SelectionChanged"></asp:Calendar>
</ContentTemplate>
</asp:UpdatePanel>