title: Symfony Class 'PDO' not found
body: <p>I just uploaded my symfony project on an online server but it gives me this error:</p>
  
  <p><img src="https://i.stack.imgur.com/8daIE.png" alt="Error picture"></p>
  
  <p>First I thought it's a problem of <code>pdo_mysql</code> extension that I should install but I found that is already installed on the server:</p>
  
  <p><img src="https://i.stack.imgur.com/CZjOA.png" alt="See this picture"></p>
  
  <p>What should I do?</p>
  
  <p><strong>EDIT :</strong></p>
  
  <pre><code>public static function getConnection(
              array $params,
              Configuration $config = null,
              EventManager $eventManager = null)
      {
          // create default config and event manager, if not set
          if ( ! $config) {
              $config = new Configuration();
          }
          if ( ! $eventManager) {
              $eventManager = new EventManager();
          }
  
          $params = self::parseDatabaseUrl($params);
  
          // check for existing pdo object
          if (isset($params['pdo']) &amp;&amp; ! $params['pdo'] instanceof \PDO) {
              throw DBALException::invalidPdoInstance();
          } elseif (isset($params['pdo'])) {
              $params['pdo']-&gt;setAttribute(\PDO::ATTR_ERRMODE, \PDO::ERRMODE_EXCEPTION);
              $params['driver'] = 'pdo_' . $params['pdo']-&gt;getAttribute(\PDO::ATTR_DRIVER_NAME);
          } else {
              self::_checkParams($params);
          }
          if (isset($params['driverClass'])) {
              $className = $params['driverClass'];
          } else {
              $className = self::$_driverMap[$params['driver']];
          }
  
          $driver = new $className();
  
          $wrapperClass = 'Doctrine\DBAL\Connection';
          if (isset($params['wrapperClass'])) {
              if (is_subclass_of($params['wrapperClass'], $wrapperClass)) {
                 $wrapperClass = $params['wrapperClass'];
              } else {
                  throw DBALException::invalidWrapperClass($params['wrapperClass']);
              }
          }
  //line 173
          return new $wrapperClass($params, $driver, $config, $eventManager);
      }
  </code></pre>
  
  <p>Thanks in advance.</p>