Fatal error: Class 'JVersion' not found in

[mersad]

سطح دسترسی فایل libraries -> cms.php رو به 777 تغییر بدید
سپس کد های زیر رو در اون قرار بدید و بعد از دخیره سطح دسترسی رو به حالت اول برگردونید !

<?php
/**
 * @package     Joomla.Libraries
 *
 * @copyright   Copyright (C) 2005 - 2012 Open Source Matters, Inc. All rights reserved.
 * @license     GNU General Public License version 2 or later; see LICENSE
 */

defined('_JEXEC') or die;

// Set the platform root path as a constant if necessary.
if (!defined('JPATH_PLATFORM')) {
   define('JPATH_PLATFORM', dirname(__FILE__));
}

// Import the cms loader if necessary.
if (!class_exists('JCmsLoader')) {
   require_once JPATH_PLATFORM.'/cms/cmsloader.php';
}

// Setup the autoloader.
JCmsLoader::setup();

// Define the Joomla version if not already defined.
if (!defined('JVERSION')) {
   $jversion = new JVersion;
   define('JVERSION', $jversion->getShortVersion());
}
// Register the location of renamed classes so they can be autoloaded
// The old name are considered deprecated and this should be removed in 3.0
JLoader::register('JRule', JPATH_PLATFORM . '/joomla/access/rule.php');
JLoader::register('JRules', JPATH_PLATFORM . '/joomla/access/rules.php');

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