File Content: validation.xml <?xml version="1.0" ?> <constraint-mapping xmlns="http://symfony.com/schema/dic/constraint-mapping" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://symfony.com/schema/dic/constraint-mapping http://symfony.com/schema/dic/constraint-mapping/constraint-mapping-1.0.xsd"> <class name="Symfony\Component\Form\Form"> <constraint name="Symfony\Component\Form\Extension\Validator\Constraints\Form" /> <property name="children"> <constraint name="Valid" /> </property> </class> </constraint-mapping> Submit