python2 code was not necessarily forwards compatible with python3. 3 was explicitly attempting to correct some regrettable choices in python2 and wasn't syntax

python2 code was not necessarily forwards compatible with python3. 3 was explicitly attempting to correct some regrettable choices in python2 and wasn't syntax compatible as a result. The effort for implementation and package maintainers to support both versions was considerable, resulting in some notable packages only supporting one or the other. In the words of the Python maintainers: We needed to sunset Python 2 so we can help Python users by improving Python faster. We released Python 2.0 in 2000. We realized a few years later that we needed to make big changes to improve Python. So in 2006, we started Python 3.0. Many people did not upgrade, and we did not want to hurt them. So, for many years, we have kept improving and publishing both Python 2 and Python 3. But this makes it hard to improve Python. There are improvements Python 2 can't handle. And we have less time to work on making Python 3 better and faster. And if many people keep using Python 2, then that makes it hard for the volunteers who use Python to make software. They can't use the good new things in Python 3 to improve the tools they make. https://www.python.org/doc/sunset-python-2/ https://www.python.org/doc/sunset-python-2/