Maximum recursion depth exceeded - Django, Python3

I am writing a blog application but I got stuck.

I'm facing the following error:

':'.join(parents + (url.namespace,)) for url in url_patterns RecursionError: maximum recursion depth exceeded

I got two urls.py files.

mysite/urls.py:

from django.conf.urls import url
from quickblog import views

urlpatterns = [
    url(r'^$', views.post_list, name='post_list'),
]

mysite/myapp/urls.py:

from django.conf.urls import include
from django.conf.urls import url
from django.contrib import admin

urlpatterns = [
    url(r'^admin/', admin.site.urls),
    url(r'', include('quickblog.urls')),
]

mysite/myapp/models.py:

from django.db import models
from django.utils import timezone


class Post(models.Model):
    author = models.ForeignKey('auth.User', on_delete=models.CASCADE)
    title = models.CharField(max_length=200)
    text = models.TextField()
    created_date = models.DateTimeField(
            default=timezone.now)
    published_date = models.DateTimeField(
            blank=True, null=True)

    def publish(self):
        self.published_date = timezone.now()
        self.save()

    def __str__(self):
        return self.title

/mysite/myapp/admin.py:

from django.contrib import admin
from .models import Post

admin.site.register(Post)

I guess I'm doing something wrong here. Any hint would be nice.