A decent 404 page is quite important. This error means that a certain page is not found. If you do not make your own 404 page, the error you will see is quite technical and can scare off your visitors. JoonextPro has a 404 page, but you can create your own if you want to.

In order to do this, do the following:

  1. Create a menu. You can have it hidden or not, it is your choice. For instance, name the menu 404-not-found.
  2. Create an article, with the minimum contents of:
    - why they came to the 404 page
    - a search option
    - a contact option, or alternatives
  3. Put step 1 and 2 together, and have the menu linked to the page.
  4. If your template does not have an error.php, make it in /templates/yourtemplate/error.php
    and fill it with the following contents:

    <?php
    /**
    * @package Joomla.Site
    * @subpackage Template.system
    *
    * @copyright Copyright (C) 2005 - 2015 Open Source Matters, Inc. All rights reserved.
    * @license GNU General Public License version 2 or later; see LICENSE.txt
    */

    defined('_JEXEC') or die;

    if (($this->error->getCode()) == '404') {
    header('Location: /404-not-found');
    exit;
    }
    ?>

  5. Make sure the red portion is equeal to the menu name you made in step 1

Voila, you now have a working 404 page that you can control yourself!