title: Response headers missing with http status code 102
body: <p>I'm currently developing a <code>REST API</code> in which I need to return a <code>102 HTTP status code</code> (processing) while I'm generating an export. </p>
  
  <p>Workflow :</p>
  
  <ol>
  <li>POST /exports
  
  <ul>
  <li>return 201 with data</li>
  </ul></li>
  <li>GET /exports/id
  
  <ul>
  <li>return 102 with data if the export is processing</li>
  <li>return 200 with data if the export is completed</li>
  </ul></li>
  </ol>
  
  <p>When I try to retrieve export data while it's processing, there are no response headers: response headers are missing with 102 HTTP status code. If I change the status code with 2xx for instance, it's working fine. I can't figure out. Is there anything specific with the 102 HTTP status code? When I say response headers are missing I mean: <code>Chrome &gt; Developer tools &gt; Network Tab &gt; Click on request &gt; Headers tab &gt; Only showing "General" and "Request Headers" (same with FF &amp; Postman)</code>.</p>
  
  <p>Used Technologies :</p>
  
  <ul>
  <li>Ubuntu 18.04 LTS</li>
  <li>PHP 7.2 (latest release)</li>
  <li>laravel/lumen 5.6.21</li>
  <li>Apache 2.4.29</li>
  </ul>
  
  <p>Controller Code :</p>
  
  <pre><code> /**
   * Return export by id
   *
   * @param int $id
   * @return \Illuminate\Http\JsonResponse
   *
   * @throws AuthorizationException
   * @throws ModelNotFoundException
   */
  public function getItem(int $id)
  {
      if($export = Export::find($id))
      {
          $this-&gt;authorize(__FUNCTION__, $export);
  
          if($export-&gt;status != Export::STATUS_COMPLETED)
          {
              return response()-&gt;json($export, 102);
          }
  
          return response()-&gt;json($export);
      }
  
      throw new ModelNotFoundException();
  }
  </code></pre>
  
  <p>Expected Request Headers :</p>
  
  <ul>
  <li>Access-Control-Allow-Origin</li>
  <li>Cache-Control</li>
  <li>Connection</li>
  <li>Content-Length</li>
  <li>Content-Type</li>
  <li>Date</li>
  <li>Proxy-Connection</li>
  <li>Server</li>
  <li>Vary</li>
  </ul>
  
  <h2>EDIT</h2>
  
  <p>I should have mentioned that it worked on my previous config :</p>
  
  <ul>
  <li>Ubuntu 17.10 LTS</li>
  <li>PHP 7.1 (latest release)</li>
  <li>laravel/lumen 5.6.16</li>
  <li>Apache 2.4.27</li>
  </ul>
  
  <p>I haven't found in any release notes what could have impacted the request answer.</p>