py launcher defaults to the free threaded executable on Windows

[JordanSchlick]

Bug report

Bug description:

Using py.exe on Windows, such as when directly executing a .py file, results in the free threaded version of Python being launched.
Even setting py.ini to launch the regular version does not fix this behavior. This results in a situation where a py file can not find modules installed by pip in the same terminal as they are run under different versions of Python.

In my case it always launches python3.14t.exe:

C:\Users\Admin>py --list
 -V:3.14t         Python 3.14 (64-bit, freethreaded)
 -V:3.14 *        Python 3.14 (64-bit)
 -V:3.11          Python 3.11 (64-bit)
 -V:3.9           Python 3.9 (64-bit)
C:\Users\Admin>py -3
Python 3.14.3 free-threading build (tags/v3.14.3:323c59a, Feb  3 2026, 16:00:26) [MSC v.1944 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>>

CPython versions tested on:

3.14

Operating systems tested on:

Windows

[JordanSchlick]

If anyone finds this and needs a jank workaround for this you can rename HKEY_LOCAL_MACHINE\SOFTWARE\Python\PythonCore\3.14t to HKEY_LOCAL_MACHINE\SOFTWARE\Python\PythonCore\0.14t
This makes it sort as the oldest version so py.exe will no longer pick it. You may need to use the user registry hive if you have a user installation instead of a system wide installation.

[StanFromIreland]

This seems like an issue in https://github.com/python/pymanager.

CC @zooba

[zooba]

That's weird, since 3.14 (not t) is clearly marked as the default in your py --list output.

Can you confirm whether you're using the new Python install manager or not? The easiest way to find out is to use the new py list command (drop the hyphens), and if you get an error then you're on the deprecated launcher. In that case, it won't be fixed.

If you are using the install manager, then it should be choosing the non-freethreaded first. Setting PYMANAGER_DEBUG environment variable equal to 1 and then launching should give us enough information.