Django：CSRF验证失败。请求中止

Question

我目前正在查看Django documentaion，用于使用post方法（https://docs.djangoproject.com/en/2.1/intro/tutorial04/）创建表单。但是，我在遇到CSRF verification failed. Request aborted错误时 在views.py

中执行vote()函数

正在使用的文件是：

views.py：

from django.http import HttpResponse, Http404
from django.shortcuts import render, get_object_or_404
from django.urls import reverse

from .models import Question
.
.
.
def vote(request, question_id):
    question = get_object_or_404(Question, pk=question_id)
    try:
        selected_choice = question.choice_set.get(pk = 
request.POST['choice'])
    except (KeyError, choice.DoesNotExitst):
        return render(request, 'polls/detail.html',{
            'question': question,
            'error_message': "you didn't select a choice"
        })
    else:
        selected_choice.votes += 1
        selected_choice.save()
    return HttpResponseRedirect(reverse('polls:results', args= 
(question.id)))

detail.html：

<h1>{{ question.question_text }}</h1>
{%if error_message%}<p><strong>{{error_message}}</strong></p>{%endif%}

<form action="{%url 'polls:vote' question.id%}" method="post">
{% csrf_token %}
{%for choice in question.choice_set.all%}
    <input type = "radio" name = "choice" id="choice{{ forloop.counter 
}}" value = "{{ choice.id }}">
    <label for="choice{{ forloop.counter }}">{{choice.choice_text}} 
</label><br>
{%endfor%}
<input type="submit" value="vote">
</form>

results.html：

<h1>{{ question.question_text }}</h1>

<ul>
{%for choice in question.choice_set.all%}
    <li>{{choice.choice_text}} -- {{choice.votes}} 
vote{{choice.votes|pluralize}}</li>
{&endfor&}
</ul>

<a href="{%url 'polls:detail question.id'%}">Vote again?</a>

这些是使用的MIDDLEWARE：

`MIDDLEWARE = [
    'django.middleware.csrf.CsrfViewMiddleware',
    'django.middleware.security.SecurityMiddleware',
    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.middleware.common.CommonMiddleware',
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
    'django.middleware.clickjacking.XFrameOptionsMiddleware',
]

urls.py：

.
.
.
app_name = 'polls'
urlpatterns = [
    path('', views.index, name = 'index'),
    path('<int:question_id>/', views.detail, name='detail'),
    path('<int:question_id>/results/', views.results, name='results'),
    path('<int:question_id>/vote/', views.vote, name='vote'),
]

但我收到此错误：