Question: I'm trying to setup the lookup field between two entities, but I can't fix this error. I've already tried these solutions but none of them worked for me(What am I doing wrong?): Django Rest Framework, improperly configured lookup field Django Rest Framework - Could not resolve URL for hyperlinked relationship using view name "user-detail" DRF Could not resolve URL for hyperlinked relationship using view name on PrimaryKeyRelatedField here's my code Models: class Category(models.Model): title = models.CharField(max_length=50, unique=True) slug = models.SlugField(max_length=80, default='') def __str__(self): return self.title class Option(models.Model): title = models.CharField(max_length=80) slug = models.SlugField(max_length=80, unique=True) description = models.CharField(max_length=250) price = models.DecimalField(max_digits=7, decimal_places=2) category = models.ForeignKey(Category, related_name='options', on_delete=models.CASCADE) photo = models.ImageField(upload_to='options', null=True) class Meta: ordering = ['title'] def __str__(self): return self.title  Serializers: class CategorySerializer(serializers.HyperlinkedModelSerializer): options = serializers.HyperlinkedRelatedField(many=True, view_name='option-detail', read_only=True) class Meta: model = Category fields = ('url', 'slug', 'title', 'options') lookup_field = 'slug' extra_kwargs = { 'url': {'lookup_field': 'slug'} } class OptionSerializer(serializers.HyperlinkedModelSerializer): category = serializers.ReadOnlyField(source='category.title') class Meta: model = Option fields = ('url', 'slug', 'title', 'description', 'price', 'category') lookup_field = 'slug' extra_kwargs = { 'url': {'lookup_field': 'slug'}, 'category': {'lookup_field': 'slug'} }  Views: class CategoryViewSet(viewsets.ReadOnlyModelViewSet): """ Returns the Category list or the requested one """ queryset = Category.objects.all() serializer_class = CategorySerializer lookup_field = 'slug' class OptionViewSet(viewsets.ReadOnlyModelViewSet): """ Returns the Option list or the requested one """ queryset = Option.objects.all() serializer_class = OptionSerializer lookup_field = 'slug'  urls: router = DefaultRouter() router.register(r'options', views.OptionViewSet) router.register(r'categories', views.CategoryViewSet) urlpatterns = [ path('', include(router.urls)), ]  This works for the Option model. When I hit the '[localhost]/options/' url, it correctly lists the options and when hitting '[localhost]/options/some-option-slug' it returns the correct option. But none of that works for the Category model. Calls to '[localhost]/categories/' retuns "Could not resolve URL for hyperlinked relationship using view name "option-detail". You may have failed to include the related model in your API, or incorrectly configured the lookup_field attribute on this field.". While calls to '[localhost]/categories/category-slug/' returns 404 Not Found. My django version is 4.0.1 and my Django Rest Framework version is 3.13.1 EDIT As suggestted by @code-apprendice, here's the output of print('router'): [<URLPattern '^options/$' [name='option-list']>, <URLPattern '^options.(?P[a-z0-9]+)/?$' [name='option-list']>, <URLPattern '^options/(?P[^/.]+)/$' [name='option-detail']>, <URLPattern '^options/(?P[^/.]+).(?P[a-z0-9]+)/?$' [name='option-detail']>, <URLPattern '^categories/$' [name='category-list']>, <URLPattern '^categories.(?P[a-z0-9]+)/?$' [name='category-list']>, <URLPattern '^categories/(?P[^/.]+)/$' [name='category-detail']>, <URLPattern '^categories/(?P[^/.]+).(?P[a-z0-9]+)/?$' [name='category-detail']>, <URLPattern '^$' [name='api-root']>, <URLPattern '^.(?P[a-z0-9]+)/?$' [name='api-root']>] The DRF correctly generated the views option-list, option-detail, category-list and category-detail

Answer: Defining the lookup_field attribute for the options in the CategorySerializer solved the problem. Here's the CategorySerializer class: class CategorySerializer(serializers.HyperlinkedModelSerializer): options = serializers.HyperlinkedRelatedField( view_name='option-detail', lookup_field = 'slug', many=True, read_only=True) class Meta: model = Category fields = ('url', 'slug', 'title', 'options') lookup_field = 'slug' extra_kwargs = { 'url': {'lookup_field': 'slug'} }  The problem was that the CategorySerializer set an explict options HyperlinkedRelatedField and it's lookup_field needs to be configured too. Feel free to edit this answer to add a deeper explanation.