SharePoint DateTimeControl Issue When Put Inside An Update Panel

All credits for this post goes to my friend and colleague Mohamed Gamal


When you add a SharePoint DateTimeControl to a webpart inside an update panel and click on the date picker icon, you will receive an "Object Expected” JavaScript error.

<SharePoint:DateTimeControl ID="dtcBirthDate" runat="server" CalendarImageUrl="/_layouts/images/calendar.gif"
CssClassTextBox="itw-longDate" DateOnly="true" LocaleId="7177" ToolTip="Example: 2000-12-31"
DatePickerFrameUrl="/_layouts/iframe.aspx" />

The solution of this error is to just include the datepicker.js file explicitly on the page inside the update panel content template as follows

<script type="text/javascript" src="/_layouts/datepicker.js"></script>

That's it. Hope this will help someone someday :)