http://www.symfony-project.org/forum/index.php/m/36830/

> I'm trying to validate a file (without yaml configuration file) in my
> backend app.
>
> My validator is executed but I can't see any error message when it fails !

Have a look here : http://www.symfony-project.org/book/1_0/10-Forms#Validators

I think you should try something like this : You are missing the

$this->getRequest( )->setError( 'yourfield', $error );

$file = $this->getRequest()->getFile('user[picture]');

if ($file)
{
        // The name field must be a text entry between 2 and 100 characters
        $myValidator = new sfFileValidator();

        $myValidator->initialize($this->getContext(), array(
                'mime_types' => array('image/jpeg', 'image/pjpeg'),
                'mime_types_error' => 'Only PNG and JPEG images are allowed',
                'max_size' => 512000,
                'max_size_error' => 'Max size is 512Kb'
        ));

        if (!$myValidator->execute(&$file, &$error))
        {
          $this->getRequest( )->setError( 'yourfield', $error );
          return false;
        }
}