问Django NoReverseMatch at /topic/ pk=

EN

class DeleteTopic(DeleteView):
model = Topic
success_url = reverse_lazy('index')

    <div class="card">
    <div class="card-body" >
        <div><h1>{{ content.topic.name }}</h1></div>
        <div class="clear">
            <div class="right">

                  <a class="btn btn-danger" href="{% url 'delete_topic' pk= %}">Delete</a>


                <div><strong>By: {{ content.topic.user.username }}</strong></div>
                <div><strong>{{ content.topic.created }}</strong></div>
            </div>

        </div>

        <div class="detail_markdown">
                {{ content.topic.content.html|safe }}
            </div>

    </div>
</div>

path('topic/<int:pk>/delete', DeleteTopic.as_view(), name='delete_topic'),

class Topic(models.Model):
    id = models.AutoField(primary_key=True)
    name = models.CharField('Topic_Name', max_length=128, blank=False) #话题名称
    content = QuillField('content', blank=False) #富文本内容
    clicks = models.IntegerField('count_click', default=0, null=False) #点击次数
    created = models.DateTimeField('创建时间', auto_now_add=True)
    # user = models.ForeignKey(UserInfo,  on_delete=models.CASCADE)
    user = models.ForeignKey(UserInfo, related_name='user_topics', on_delete=models.CASCADE)
    # subject = models.ForeignKey(Subject,  on_delete=models.CASCADE)
    subject = models.ForeignKey(Subject, related_name='subject_topics', on_delete=models.CASCADE)

    class Meta:
       verbose_name = '话题表'
       verbose_name_plural = verbose_name
       ordering = ['-id']