include app name
https://github.com/codingforentrepreneurs/eCommerce/blob/fc97ee8fd094a47aeb47ad7b25cf2d5a04c78fe8/src/ecommerce/urls.py
url(r'^products/',include(('products.urls', 'products'), namespace='products')),
showing error on django 2.0+ without the above change
As Justin explains in his videos, the course was specifically written for the LTS version of Django (1.11). You can read here for more information and discussion.
Remove the namespace parameter from the url and try to add
app_name = 'products'
in products->urls.py file.
simply add the app_name = 'products' in the url.py of the product before the urlpatterns