old_contents: from django.conf.urls import patterns, url
  
  from .views import CategoriesList, GalleryDetail, StoryDetail
  
  urlpatterns = patterns('category.views',
      url(r'^gallery/categories/(?P<slug>.+)/$', GalleryDetail.as_view(), name='gallery-detail'),
      url(r'^stories/categories/(?P<slug>.+)/$', StoryDetail.as_view(), name='story-detail'),
      url(r'^categories/$', CategoriesList.as_view(), name='category-list'),
      url(r'^gallery/$', 'gallery_home_page', name='gallery-home-page')
  )
  
new_contents: from django.conf.urls import patterns, url
  
  from .views import CategoriesList, GalleryDetail, StoryDetail
  
  urlpatterns = patterns('category.views',
      url(r'^categories/$', CategoriesList.as_view(), name='category-list'),
      url(r'^categories/(?P<slug>.+)/$', StoryDetail.as_view(), name='category-detail'),
      url(r'^stories/categories/(?P<slug>.+)/$', StoryDetail.as_view(), name='story-detail'),
      url(r'^gallery/categories/(?P<slug>.+)/$', GalleryDetail.as_view(), name='gallery-detail'),
  
      url(r'^gallery/$', 'gallery_home_page', name='gallery-home-page')
  )
  
subject: Add the missing category-detail urlconf to not to break bookmarked users