Django is adding slash into dynamic URL segment

I have a dynamic url configured like so:

What is a NoReverseMatch error, and how do I fix it?

I have some code and when it executes, it throws a NoReverseMatch, saying:

What is a NoReverseMatch error, and how do I fix it?

I have some code and when it executes, it throws a NoReverseMatch, saying:

Django cannot find page with multiple similar URL paths

I am trying to create a Django site with different views/models spanning from the same level of the URL structure.