How to force a PostBack when Ajax mode is enabled

Note that AJAX mode uses an UpdatePanel which disables controls from doing PostBacks. The solution would be to force the PostBack on specific controls by adding the below code in the Page_Load event of the page:

protected void Page_Load(object sender, EventArgs e) {
  ScriptManager scriptManager = ScriptManager.GetCurrent(this.Page);
  //Further code goes here....