Just updated to an M1 Max. When downloading Sourcetree it wouldn't let me open it directly.

But I was able to launch it by locating the application in the Finder -> Applications -> Sourcetree

When I checked for updates surprisingly (even though I just downloaded) there were some.

It then asked me to download dev tools for Python and after proceeding Sourcetree seems to work just fine.

So I wasn't as locked out as it initially felt, but I figured I'd share my path here in case anyone else has the same issue.

Beware! macOS 12.3 breaks SourceTree completely if you use Mercurial. There are some possible workarounds by installing a newer Mercurial that uses Python 3.10 and linking it up, but not working for everyone.

When I upgraded my laptop to MacOS Monterey 12.2.1 I saw this message. It said:

"SourceTree" needs to be updated

This app will not work with future versions of macOS and needs to be updated to improve compatibility. Contact the developer for more information.

When I clicked "Learn more" I saw the same page as Pierre-Yves Beaudouin and Bernard Mongold mentioned above.

This happened to me today with 4.1.5, though it waited until I opened Preferences.

(Keep in mind macOS will only show this warning once per macOS release.)

Rather than it being an issue with regard the app not being Universal, I suspect that it's because it references Python 2 rather than Python 3. Python 2.x is EOL and MacOS will no longer support Python 2.x in the next version.

I got the same popup on an Intel machine. When clicking on "Learn more", it opened the page https://www.python.org/doc/sunset-python-2/ however.