 <p>MySQLi is not a driver for PDO. It is a standalone class. PDO has the following drivers:</p> <ul> <li>CUBRID (PDO)</li> <li>MS SQL Server (PDO)</li> <li>Firebird (PDO)</li> <li>IBM (PDO)</li> <li>Informix (PDO)</li> <li>MySQL (PDO)</li> <li>MS SQL Server (PDO)</li> <li>Oracle (PDO)</li> <li>ODBC and DB2 (PDO)</li> <li>PostgreSQL (PDO)</li> <li>SQLite (PDO)</li> <li>4D (PDO)</li> </ul> <p>More information you can find here: <a href="http://php.net/manual/de/pdo.drivers.php" rel="nofollow">http://php.net/manual/de/pdo.drivers.php</a><br> You have to remove the <code>i</code> from the dsn: <code>mysql:host=127.0.0.1;dbname=app</code></p>