You're missing that Python 3 is clearly labeled as a breaking change? He is talking about changes that are not labeled as breaking changes but do infact break things.

One major breaking release in how many years, clearly announced as such and with parallel support for the old version for a long time (so you didn't just update python and it broke). Fits quite well under "almost never breaks".

Or have their been issues with minor releases? I haven't come across any I can remember, but I might be wrong. Maybe some things were deprecated and then removed?

Python 3 is a similar language with a similar name to Python 2. It shouldn’t be considered an update, nor applied as one.

I get the idea, but this is user hostile. If it shouldn't be seen as an upgrade, it should have had a new name. :( Especially if it is going to be a forced migration someday? (I'm assuming python2 support will eventually stop?)

Yet a huge number of Python modules are both valid Python 2 code and Python 3 code.

Sure, they're similar enough that a single file can be valid in both with less effort than most language pairs. That doesn't mean it's an update, any more than C is an upgrade to Lisp because I can make a file that's valid in both.

Yet the Python 3 executable has the same name as the Python 2 executable...

Only on Arch and Windows... All other Linux distribution have python3 and macOS binary is also python3.

No they don't. At least one of them has a number after it.

I got both Python 2 and Python 3 installed on my machine, from the official distribution, and both have "python.exe", no numbers.

If you're talking about Python 2 -> 3, I think you're misunderstanding his point.

Can't edit orig comment...yes I misunderstood the point about explicit breaking changes. I recently watched Rich Hickey's "spec-ulation" talk referenced elsewhere in this thread, which takes an extreme view (tl;dr SemVer sucks and we shouldn't have breaking changes ever), so that's where my mind was. Thanks for the clarity, all.

He says Python packages, many of which bend over backwards to maintain backwards compatibility. (I wish Django were one of them)