FormException class not found

[franckgre]

Trying to use AjaxAutocomplete with Symfony 2.3, I've the following error :

FatalErrorException: Error: Class 'Symfony\Component\Form\Exception\FormException' not found in D:\FranckData\www181\lastsymf\vendor\shtumi\useful-bundle\Shtumi\UsefulBundle\Form\Type\AjaxAutocompleteType.php line 52

It seems that the class FormException was deprecated with Symfony 2.2 and removed with Symfony 2.3

Thanks