Python 3.5-3.8 and Windows Vista

[adang1345]

Python 3.5-3.8 officially support Windows Vista. However, the current builds were done with Visual Studio 2022 v17.14, which uses version 14.44.35211.0 of the MSVC++ runtime redistributable DLLs, which require Windows 7 and newer.

For Python 3.5-3.6, the current packaged version of vcruntime140.dll is 14.12.25810.0, which is strange and I'm not sure where it came from.

For Python 3.7-3.8, the current packaged version of vcruntime140.dll is 14.44.35211.0, which is expected based on how I built them and is too new.

According to https://github.com/abbodi1406/vcredist, the most recent MSVC++ runtime redistributable version that supports Windows Vista is 14.32.31332.0. From the table at https://learn.microsoft.com/en-us/lifecycle/faq/visual-c-faq#what-are-the-support-dates-for-visual-c---redistributable--msvc-runtime-libraries--and-msvc-toolset-versions-2015--2017--2019--2022--and-later-, that likely corresponds with Visual Studio 2022 v17.2.

Rebuild using the 14.32 build tools to ensure compatibility with Windows Vista.

[Vangelis66]

Python 3.5-3.8 officially support Windows Vista.

Well, it isn't your own mistake 😉 just a PSF one 😠, but Vista SP2 was EoL'ed with CPython-3.7, last security-fix version being 3.7.17 (and your own 3.7.17_x86 builds work fine on this old Vista SP2 32-bit laptop 👍 ) ...

Below, a link to yt-dlp issue tracker from 2023, where I, once again, explained to them how things stand wrt Vista SP2 vs CPython versions:

yt-dlp/yt-dlp#7803 (comment)

(and two previous (2021) contributions of mine there:
yt-dlp/yt-dlp#93 (comment)
yt-dlp/yt-dlp#390)

According to abbodi1406/vcredist, the most recent MSVC++ runtime redistributable version that supports Windows Vista is 14.32.31332.0.

This is, indeed, correct 😄 ; Microsoft also f*cked up there, because their last Vista-compatible installer for their MSVC++ 2015-2022 redistributable package (VC_redist.x86.exe) was for version 14.31.30919.0; however, the payload of subsequent installers (but NOT the installers themselves 😡 ) remained Vista-compatible up-to-and-including v14.32.31332.0; the next version, 14.34.31823.0, introduced incompatibilities with Vista's kernel, namely in files:

concrt140.dll
msvcp140.dll
msvcp140_1.dll
msvcp140_2.dll
msvcp140_atomic_wait
vcamp140.dll
vccorlib140.dll

which made two function calls,

TryAcquireSRWLockExclusive in kernel32.dll,
CoGetApartmentType in ole32.dll,

only present on Win7+ 😞 ...

[Vangelis66]

For Python 3.7-3.8, the current packaged version of vcruntime140.dll is 14.44.35211.0, which is expected based on how I built them and is too new.

If I'm not mistaken, your own builds only bundle file vcruntime140.dll, not other files of the corresponding MSVC++2022 runtime (e.g. file msvcp140.dll); I can also confirm that versions of file vcruntime140.dll beyond 14.32.31332.0 do remain Vista-compatible; even the latest one, 14.44.35211.0, is fine here (actual Vista SP2 install, not VM; have various applications needing it working OK here 👍 ) ...

[adang1345]

Thanks, it's good to know that newer versions of vcruntime140.dll do work on Windows Vista. That saves me a lot of time. With that knowledge, I won't need to rebuild with an earlier version of the Visual Studio build tools.

As for the other issue I found, I think I figured out why my builds of Python 3.5-3.6 are including the wrong vcruntime140.dll version 14.12.25810.0; I'll just work on fixing this instead. I don't know whether there actually are any issues with including a version this old, but I think it's simple enough to fix, so I'll go ahead with it.

[Vangelis66]

... On the subject of CPython and Vista compatibility, may I be so cheeky 😄 as to ask whether you'd consider backporting support down to NT 6.0 (Vista, WS2008R1) in your PythonWin7 offerings?

You have provided (and continue to provide 👍 ) an invaluable service 🥇 to the retrocomputing communities, namely the Win7 one, with your Win7-compatible py3.9+ builds; these are already being put into good use by compiling Win7-compatible yt-dlp (both x86 and x64) builds for Win7 users, because the yt-dlp team are adamant on ceasing support for any CPython version not officially supported by the PSF themselves; thus, py3.8 was dropped last year and now py3.9 will be imminently dropped...

However, the NT6.0 crowd 😉 has been left without something concrete 😢 ; FTR, a member of the MSFN forums has come up with source-patched and self-recompiled versions of py3.8.13, py3.9.13, py3.10.18 and py3.11.4 (nothing newer as I write this), but these "assemblies" have non-standard configuration and mainly target WinXP SP3 32-bit hosts, with legacy CPUs only supporting the SSE instruction set...

I have taken a closer look at your PythonWindows py3.8.x builds and your PythonWin7 py3.9.x, py3.10.x, py3.11.x, py3.12.x, py3.13.x builds; the installers have been extracted with UniExtract2 and/or the embed-win32 packages have been extracted.

The one file that presents the incompatibilities with Vista SP2 is always the python3x.dll one: in more detail:

python38.dll (PythonWindows), python39.dll (PythonWin7) and python310.dll (PythonWin7), all three have ONLY ONE Win7+ kernel32.dll function:

GetActiveProcessorCount

python311.dll (PythonWin7), python312.dll (PythonWin7) and python313.dll (PythonWin7), all three have ONLY TWO Win7+ kernel32.dll functions:

GetActiveProcessorCount (case of python[38,39,310].dll)

SetWaitableTimerEx

If I HexEdit GetActiveProcessorCount to GetSystemInfo in the first group of DLLs, I can make py3.8.x/py3.9.x/py3.10.x launch on this Vista SP2 32-bit machine; likewise, if I HexEdit GetActiveProcessorCount to GetSystemInfo and SetWaitableTimerEx to SetWaitableTimer in the second group of DLLs , I can make py3.11.x/py3.12.x/py3.13.x launch, too, on the Vista SP2 32-bit machine; but this is hacking binary files, there's no telling how the actual Python code will behave on a remote scenario...

Optimally, the Vista-incompatible Python code should be excised from source and then the source recompiled, with compiler targeting at minimum NT 6.0; hopefully, Vista-compatible builds would be produced...

Thanks for your precious time reading this ❤️ ; any personal thoughts on achieving NT 6.0 support in your py3.8+ builds would be welcome/highly appreciated 😄 ...

Thanks for all that you already do 👍 , kindest regards from a Vista die-hard 😉 ...

[Vangelis66]

version 14.12.25810.0; (redacted) I don't know whether there actually are any issues with including a version this old

... There shouldn't be any, unless, of course, that old a file has unpatched security vulnerabilities that were patched in later/more recent versions; but this is a Microsoft file, closed source, "they" are seldom transparent in what - and how - "they" patch 😉 ...

[adang1345]

Fixed builds of Python 3.5 and 3.6 are done. It turns out that only the NuGet and embeddable distributions had an old version of vcruntime140.dll and needed fixing.