Mi problema:

Publico por ajax en mi controlador el formulario.

 $.ajax({ url: "test.php", type: "post", data: new FormData(document.querySelector("form")) , success: function (response) { // You will get response from your PHP page (what you echo or print) }, error: function(jqXHR, textStatus, errorThrown) { console.log(textStatus, errorThrown); } });

y mi controlador

 <?php namespace App\Controller; /*¤controller_namespace¤*/ use ... /** * @Route("admin/article") */ class ArticleController extends AbstractController { /** * @Route("/upload", name="upload", methods={"GET","POST"}) */ public function upload(Request $request, FileUploader $fileUploader): Response { /*¤new_begin¤*/ $article = new Article(); $form = $this->createForm(ArticleType::class, $article); $form->handleRequest($request); /*¤new_form¤*/ //return error for ajax only if ($request->isXmlHttpRequest() && !$form->isValid()) { return new jsonResponse(getErrorMessages($form), 415); } }}

Symfony no detecta la llamada ajax en el controlador. Envío un formulario no válido pero la función isXmlHttpRequest no detecta la llamada ajax.