XML解析错误：找不到根元素（django + AJAX）

Question

I'm trying to send a POST request using formdata. But this error comes out in FF and status code 400. XML Parsing Error: no root element found Location: http://127.0.0.1:8000/ajax/set_user_profile/ . On the server logs, the request to the function does not even reach. I have another POST request that works without problems, but this one does not work. Also i'm checked html with w3c validator. all its ok.

JS

function set_user_profile(e){
  e.preventDefault();
  let csrf_token = document.getElementById("profile-menu-csrf").value;
  let form = document.getElementById("profile-form");
  let formData = new FormData(form);
  let xhr = new XMLHttpRequest();
  xhr.open('POST', '/ajax/set_user_profile/', true);
  xhr.setRequestHeader('Content-Type', 'multipart/form-data')
  xhr.setRequestHeader('X-CSRFToken', csrf_token);
  xhr.onreadystatechange = function(){
      if(xhr.readyState === 4 ){
          if (xhr.status === 200){
              console.log('ok');
          }
          else{
              console.error(xhr.status);    
          }
      }
  };
  xhr.send(formData);
  }

HTML form like this

<form id="profile-form">
  <input name="csrfmiddlewaretoken" value="${csrf_token}" type="hidden" id="profile-menu-csrf">
  <input type="text"/>
  <textarea></textarea>
  <input type="text"/>
  <input type="text"/>
  <input type="text"/>
  <input type="submit"/>
</form>

URL conf

urlpatterns = [
url(r'^admin/', admin.site.urls),
url(r'^login/$', generic.RedirectView.as_view(url='/accounts/login', permanent=False), name='login'),
url(r'^register/$', views.registration, name='registration'),
url(r'^webchat/$', views.home, name="home"),
url(r'^ajax/add_chat/$', ajax.add_chat, name='add_chat'),
url(r'^ajax/update_chats/$', ajax.update_chats, name='update_chats'),
url(r'^ajax/load_messages/$', ajax.load_messages, name='load_messages'),
url(r'^ajax/who_online/$', ajax.who_online, name="who_online"),
url(r'^ajax/get_user_profile/$', ajax.get_user_profile, name="get_user_profile"),
url(r'^ajax/set_user_profile/$', ajax.set_user_profile, name='set_user_profile'),
] 

Django view just for testing

def set_user_profile(request):
    data = {}
    data['ok'] = 'ok'
    return JsonResponse(data)

Answer 1

Damn, it was so easy. Just need to remove the header content-type.