Symfony3 returns "internal server error 500" only in prod

Question

we are getting this 500 error but only in prod environment. This app works fine in DEV/QA env

Even in prod this app works fine until you send a form to edit some data in data base. Then, when

debuggin I realized that this error occurs here:

        return new JsonResponse(
            array(
                'message' => $message,
                'form' => $this->renderView(
                    $template,
                    array(
                        'cv' => $cv,
                        $formName => $form->createView(),
                    )
                ),
                'view' => $view
            ),
            $code
        );

apparently the path for the template in $view not exist. But it makes no sense because it does exists, even the app calls this template in other context and just works fine.

My english is not good so I hope you can understand me. Thank you!

EDIT: Symfony and server error logs has been already checked, but found nothing about this error.