title: Parameter "" for route "" must match "[^/]++" ("" given) to generate a corresponding URL
body: <p>I have this Facade entity, everytime I try to modify a form where my below twig is included, it returns this error :</p>
  
  <pre><code>An exception has been thrown during the rendering of a template ("Parameter "buildings_id" for route "addFacade" must match "[^/]++" ("" given) to generate a corresponding URL.").
  </code></pre>
  
  <p>My controller action : </p>
  
  <pre><code>/**
   * @Route("/{id}/card", name="business_card", methods="GET|POST|DELETE", defaults={"business_id"=1})
   * @param Request $request
   * @param Business $business
   * @return Response
   */
  public function show_card(Request $request, Business $business): Response
  {
  
      $businessCard = $business-&gt;getBusinessCard();
  
      $formCard = $this-&gt;createForm(BusinessCardType::class, $businessCard);
      $formCard-&gt;handleRequest($request);
  
      if (($formCard-&gt;isSubmitted() &amp;&amp; $formCard-&gt;isValid())) {
  
          $businessCard = $formCard-&gt;getData();
          $em = $this-&gt;getDoctrine()-&gt;getManager();
  
          $em-&gt;persist($businessCard);
          $em-&gt;flush();
  
          return $this-&gt;redirectToRoute('business_card', ['id' =&gt; $business-&gt;getId()]);
      }
  
      $dict = array('A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J');
      return $this-&gt;render('business/card.html.twig', ['business' =&gt; $business, 'formCard' =&gt; $formCard-&gt;createView(), 'dict' =&gt; $dict]);
  }
  </code></pre>
  
  <p>My twig template :</p>
  
  <pre><code>{% for buildingsInfo in business.businessCard.buildingsInfos %}
  {% set idBuildingsInfo = idBuildingsInfo|merge([buildingsInfo.id]) %}
  &lt;a class="btn btn-outline-primary mb-3" href="{{ path("addFacade",{"buildings_id": idBuildingsInfo[j] }) }}"&gt;Ajouter une façade&lt;/a&gt;
  {% endfor %}
  </code></pre>
  
  <p>I tried to dump my <code>idBuildingsInfo</code> variable, but all values of the array are numbers (no null values). I also tried to add a default value in my controller for parameter <code>buildings_id</code> but it does not seem to change anything.</p>