[dfinninger]

Django was actually fine. They had the same codebase running on Python 2 and three, so you could update whenever. Since Django includes so many batteries, I didn’t have any trouble porting that over.

However, early versions of Python 3 were slower than Python 2, and also some breaking changes were getting rolled back (e.g. PEP-414, which was targeting Python 3.3), which contributed to a lot of library authors dragging their feet in upgrading their support.

So, yes, it was libraries causing the most headaches, but there was a sense at the time of wondering when the upgrade would become “real”. Depreciating py2 took 11 years after the release of 3.0.