[Semaphor]

> as Java's Python 2 problem is the transition into Java 9

Binary incompatibility between 7 and 8 as well, we got an enterprise product that got bought by SAP and will eternally be stuck on Java 7, but at least unlike the other one, it doesn’t require much maintenance as it’s only used internally ;)

> Python 2 => 3 also has the issue that some things don't exist in Python 3, or are done in incompatible ways.

What doesn’t exist? I don’t like python, but it always seemed like those changes were all relatively minor?

[pjmlp]

The way unicode was handled, integer division semantics, some libraries went away, and a few other things change enough that 2to3 wouldn't handle everything, which in a dynamic language is a big pain to track down in a huge codebase.

Naturally some changes on the C API for native libraries as well.

[Semaphor]

Fair enough, thought that still sounds like things where an upgrade path is available, just not automatically, instead of "you have to throw the code away because it simply doesn’t work anymore".