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Windows embeddable distribution outputs WARN: Could not find the platform standard library directory! #155254
Description
Bug report
Bug description:
When the Windows embeddable distribution version 3.15.0rc1 is extracted and python.exe is run, a warning is shown.
WARN: Could not find the platform standard library directory! The Python 'home' directory was set to 'C:\\Users\\User\\Downloads\\python-3.15.0rc1-embed-amd64', is this correct?
Python 3.15.0rc1 (tags/v3.15.0rc1:37e98da, Aug 4 2026, 11:37:18) [MSC v.1951 64 bit (AMD64)] on win32
>>>
The warning first appears in 3.15.0a7. It is not present in 3.15.0a6 or 3.14.7. #145273 looks suspicious.
CPython versions tested on:
3.15
Operating systems tested on:
Windows
Activity
picnixz commentedon Aug 5, 2026
cc @zooba
StanFromIreland commentedon Aug 5, 2026
I think it's a duplicate of #148750, based on Steve's comment there, but Windows things are scary so I'll leave this to someone else. ;-)
zooba commentedon Aug 11, 2026
Yes, I think it's the same issue, and it's critical now because it's going to block PyManager updates (I expect python/pymanager#397 will fail in CI, as it's failing locally for me).
Still don't have time to look into it (I'm meant to be AFK and recovering right now), but will prioritise and block releases on this once I'm back online properly.
test.pythoninfofails on Windows in Azure CI #148750zooba commentedon Aug 17, 2026
@chris-eibl found that this issue pre-dates #148750, so we should solve both, but they're likely independent.
zooba commentedon Aug 18, 2026
Tagging this as a release blocker as well, since new extra/unnecessary output can be a major regression for users. But the fix (just disable the warning when the user has configured paths themselves) should be safe enough.
chris-eibl commentedon Aug 18, 2026
Debugging using
cpython/Modules/getpath.py
Line 29 in c5168ea
shows that
cpython/Modules/getpath.py
Lines 777 to 779 in c5168ea
fires because
platstdlib_dir="<embedded-dir>\DLLs", which does not exist in the embedded case. IIUC, it is set herecpython/Modules/getpath.py
Lines 740 to 741 in c5168ea
where
cpython/Modules/getpath.py
Line 194 in c5168ea
and
sys.platlibdir="DLLs". This has been the case for ages, but I wonder whether this should be an empty string in the embedded case?zooba commentedon Aug 18, 2026
The problem is that there's no "embedded case" - we only have one build, and the adaptation is dynamic.
Suppressing the warning when a
._pthfile is used matches the same suppression whenPy_SetPathor similar have been used, I think it was just missed.gh-155254: Avoid warning about missing stdlib when using _pth files (G…
[3.15] gh-155254: Avoid warning about missing stdlib when using _pth …