Reverse for ‘blog_detail’ with arguments ‘(’’,)’ not found. 1 pattern(s) tried: [‘blog\/(?P<blog_id>[^/]+)$’]
将
<a href="{% url 'blog_detail' blog_id %}"> <h3>{{ blog.title }}</h3>
改成
<a href="{% url 'blog_detail' blog.id %}"> <h3>{{ blog.title }}</h3>