Python 2 -> 3 change really was painful for Python community, but PHP does these almost fundamental breaking changes so often, that maybe people just get used to it? I haven't really followed Python past version 2, but I think they are less likely to ever do such amount of breaking changes.
There must be a lot of unmaintained PHP codebases that will break if PHP is updated by hosting provider etc. Someone must be pulling a lot of hairs because of this.
Edit: Those dogpiling there, I rest my case with josefresco's comment:
https://news.ycombinator.com/item?id=33907628
It's painful. Dropping dynamic properties? That will be a lot of fun. WordPress is probably biggest segment for PHP usage.
I have a private (non-internet) web-app that's still on PHP6.5; I like the new PHP features, but upgrading private code to conform to PHP 7 and 8 looks a lot like make-work. I wish it shipped with good upgrade tools.
[Edit] @darkwater (below) is correct; I meant PHP 5.6. PHP6 was some kind of abortion - I can't remember the story.
I'm doing this quite often as I maintain some code-bases that have backward compat down to PHP 5.3 as the baseline. So if you're looking for forward compatibility of your PHP 5.6 codebase to 7.x and 8.x (incl. 8.2), its not so much of work.
If you need an upgrade tool, have different PHP versions at hand and load each file on the CLI and PHP will show you the deprecation warnings. It then depends a bit on the code (each()/next()/reset() family undergone some changes if not removals in 8? so you have to replace with some different syntax) but most of the rest is only deprecation warnings that can be overcome with #attributes "annotations" that are just comments prior php 8.
tooling could be better especially if you're running from low versions, thought. but using php on the cli directly brings you quite far and on speed already for most things in my personal experience. git, find and xargs are your friends.