Why would django fail with server 500 only when Debug=False AND db is set to production database on Heroku?

Question

When we run $ python manage.py runserver --settings=project.settings.local there are 4 different possible combinations:

1. Debug=True && DB=l

Answer 1

something here helped me:

I had a static css file link (and honestly, it had just a few lines), once I removed the link, and inserted into a tag in my main.html, it worked just fine: with DEBUG=False

:D