Nach Neuinstallation => Fatal error: Class 'JControllerAdmin' not found in: - Im Backend sind einige Buttons nicht funktional

<?php
/**
* @package Joomla.Administrator
* @subpackage com_content
*
* @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;

/**
* Articles list controller class.
*
* @since 1.6
*/
class ContentControllerArticles extends JControllerAdmin
{-------------------------------------Zeile 18--------------------------------
/**
* Constructor.
*
* @param array $config An optional associative array of configuration settings.
*
* @see JController
* @since 1.6
*/
public function __construct($config = array())
{
parent::__construct($config);

// Articles default form can come from the articles or featured view.
// Adjust the redirect view on the value of 'view' in the request.
if ($this->input->get('view') == 'featured')
{
$this->view_list = 'featured';
}

$this->registerTask('unfeatured', 'featured');
}

/**
* Method to toggle the featured setting of a list of articles.
*
* @return void
*
* @since 1.6
*/
public function featured()
{
// Check for request forgeries
JSession::checkToken() or jexit(JText::_('JINVALID_TOKEN'));

$user = JFactory::getUser();
$ids = $this->input->get('cid', array(), 'array');
$values = array('featured' => 1, 'unfeatured' => 0);
$task = $this->getTask();
$value = JArrayHelper::getValue($values, $task, 0, 'int');

// Access checks.
foreach ($ids as $i => $id)
{
if (!$user->authorise('core.edit.state', 'com_content.article.' . (int) $id))
{
// Prune items that you can't change.
unset($ids[$i]);
JError::raiseNotice(403, JText::_('JLIB_APPLICATION_ERROR_EDITSTATE_NOT_PERMITTED'));
}
}

if (empty($ids))
{
JError::raiseWarning(500, JText::_('JERROR_NO_ITEMS_SELECTED'));
}
else
{
// Get the model.
$model = $this->getModel();

// Publish the items.
if (!$model->featured($ids, $value))
{
JError::raiseWarning(500, $model->getError());
}

if ($value == 1)
{
$message = JText::plural('COM_CONTENT_N_ITEMS_FEATURED', count($ids));
}
else
{
$message = JText::plural('COM_CONTENT_N_ITEMS_UNFEATURED', count($ids));
}
}

$view = $this->input->get('view', '');

if ($view == 'featured')
{
$this->setRedirect(JRoute::_('index.php?option=com_content&view=featured', false), $message);
}
else
{
$this->setRedirect(JRoute::_('index.php?option=com_content&view=articles', false), $message);
}
}

/**
* Proxy for getModel.
*
* @param string $name The model name. Optional.
* @param string $prefix The class prefix. Optional.
* @param array $config The array of possible config values. Optional.
*
* @return JModel
*
* @since 1.6
*/
public function getModel($name = 'Article', $prefix = 'ContentModel', $config = array('ignore_request' => true))
{
$model = parent::getModel($name, $prefix, $config);

return $model;
}

/**
* Function that allows child controller access to model data
* after the item has been deleted.
*
* @param JModelLegacy $model The data model object.
* @param integer $ids The array of ids for items being deleted.
*
* @return void
*
* @since 12.2
*/
protected function postDeleteHook(JModelLegacy $model, $ids = null)
{
}
}