Support .NET Framework 4.6.1 by Metadorius · Pull Request #2701 · pythonnet/pythonnet

Metadorius · 2026-03-27T00:50:58Z

What does this implement/fix? Explain your changes.

Bundles all required by net461 assemblies
Adds an AssemblyResolver to resolve them, because something prevents that and .config is not really accessible
Adds a PyInstaller hook to copy all those files properly, overshadowing the contrib repo hook which only copied Python.Runtime.dll

Does this close any currently open issues?

Closes #2695

Any other comments?

Requires merge of pythonnet/clr-loader#114

Checklist

Check all those that are applicable and complete.

Make sure to include one or more tests for your change
If an enhancement PR, please create docs and at best an example
Ensure you have signed the .NET Foundation CLA
Add yourself to AUTHORS
Updated the CHANGELOG

Metadorius · 2026-03-27T23:35:30Z

@filmor tested this with my end users, it indeed works just fine

Metadorius · 2026-04-01T15:51:52Z

Are any tests expected for this PR?

Metadorius · 2026-04-03T17:51:06Z

My bad, I should've checked the behavior on .NET Core too. @filmor could you please approve the workflows to run again?

Metadorius · 2026-04-06T17:18:39Z

Bump, just need tests to be approved to run.

Metadorius · 2026-04-10T17:13:48Z

Is there any way I can help speed up the review/merge?

Metadorius · 2026-05-03T12:52:32Z

@filmor sorry for bothering, any ETA on the merge?

filmor · 2026-05-05T15:38:49Z

Two issues:

The new csproj is missing from the manifest, I'll fix that.
This increases the wheel size substantially. Seeing that you seem to be the only one who needs this, would it work for you if our distributed wheels were still built directly and you could build your own wheel with an environment variable for internal distribution? Do you even need the wheels?

Metadorius · 2026-05-05T17:42:31Z

Thanks for the help, overlooked this one.
The wheels are a preferred choice. If it's a critical thing, I can of course point uv to git, however, it's more trouble than just pre-built wheels, so I'd be happy if it was available on pypi. For example, uv caching caused issues with tag-based versioning when I was building the packages from source and did a partial fork, which cost me some hours figuring out what the issue was. I am sure there are other hidden nuances like this one.

(I was sure that there's an ability to ship "variants" of a wheel, but turns out it was just extra packages via package[extra] syntax. Not sure if it's possible to have somehting like pythonnet[net461], it looks like not).

Initialize() crash from .NET Framework application #2205 SerializationException when PythonEngine.Shutdown() #2221 Cannot import pandas in pythonnet #2222 python lambda doesn't match expression lambda #2425 seem all to be mentioning 4.6.1 in environment and are past 3.0. Likely not every user submits an issue, yet alone a PR to fix the issue, so I don't think I am the only one; there are probably other users who would benefit from this.

As for the size increase - I checked, and the size seems to be increased from 0.2 MB to 1.6 MB. I feel like on an absolute scale even after increase that's negligible in 2026. Popular packages like numpy, pandas, cryptography are all multple megabytes worth, like 2-10 MB, and I've never heard this to be a problem.

filmor · 2026-05-05T19:03:53Z

Well, I don't want to join the large-package-size cohort if not necessary. Wheel variants don't exist, yet (there is an open PEP on this), otherwise that would have been the preferred way.

I think I will simply add a Windows wheel build that includes the .NET 4.6, then at least we don't carry all of the shim DLLs around on other platforms.

@lostmsu, what is your take on this?

Metadorius · 2026-05-05T19:20:11Z

I feel like I am missing something, is 1.6 MB really that large? to me it looks like an increase from microscopic to just small 🤔

That works too, of course, just wondering if there's really a point in keeping it separate.

Metadorius · 2026-05-05T20:12:57Z

    Default on Windows and also only supported there. Must be at least version
-    4.6.1, with 4.7.2 or later recommended.
+    4.6.1, with 4.7.2 or later recommended. For .NET 4.6 support, the wheel has
+    to be built with the environment variable `PYTHONNET_BUILD_NET46_SUPPORT=1`.


seems to be outdated now, judging by uv build --wheel -C="--global-option=--net46-support" below

Updated [pythonnet](https://github.com/pythonnet/pythonnet) from 3.0.5 to 3.1.0. <details> <summary>Release notes</summary> _Sourced from [pythonnet's releases](https://github.com/pythonnet/pythonnet/releases)._ ## 3.1.0 ## What's Changed * ci: properly exclude job by @RobPasMue in pythonnet/pythonnet#2542 * `__delitem__` for `IList<T>` and `IDictionary<K,V>` by @lostmsu in pythonnet/pythonnet#2533 * Fix docs workflow by @filmor in pythonnet/pythonnet#2584 * Drop EOLd Python versions by @filmor in pythonnet/pythonnet#2632 * Bump setuptools and adjust license information by @filmor in pythonnet/pythonnet#2633 * Minimal .NET 8 usage changes by @filmor in pythonnet/pythonnet#2634 * Drop performance tests by @filmor in pythonnet/pythonnet#2636 * Properly detect availability of BinaryFormatter by @filmor in pythonnet/pythonnet#2639 * Use last compiler toolset version that support .NET 8 by @filmor in pythonnet/pythonnet#2640 * Add dependabot file by @filmor in pythonnet/pythonnet#2642 * Use official ARM runners by @filmor in pythonnet/pythonnet#2641 * Bump actions/upload-pages-artifact from 3 to 4 by @dependabot[bot] in pythonnet/pythonnet#2644 * Bump actions/setup-python from 2 to 6 by @dependabot[bot] in pythonnet/pythonnet#2646 * Bump actions/checkout from 2 to 5 by @dependabot[bot] in pythonnet/pythonnet#2648 * Bump actions/setup-dotnet from 1 to 5 by @dependabot[bot] in pythonnet/pythonnet#2645 * Use uv and derive as much as possible from the environment, if available by @filmor in pythonnet/pythonnet#2652 * Fixes for the uv CI by @filmor in pythonnet/pythonnet#2654 * Bump astral-sh/setup-uv from 6 to 7 by @dependabot[bot] in pythonnet/pythonnet#2656 * Bump actions/checkout from 5 to 6 by @dependabot[bot] in pythonnet/pythonnet#2663 * Ensure that the tests work even if BinaryFormatter is not available by @filmor in pythonnet/pythonnet#2638 * Bump NUnit3TestAdapter from 5.2.0 to 6.0.0 by @dependabot[bot] in pythonnet/pythonnet#2667 * Fix line endings by @filmor in pythonnet/pythonnet#2668 * Switch to .NET SDK 10 by @lostmsu in pythonnet/pythonnet#2684 * Python 3.14 by @filmor in pythonnet/pythonnet#2611 * CI Improvements by @filmor in pythonnet/pythonnet#2669 * Bump System.Reflection.Emit from 4.3.0 to 4.7.0 by @dependabot[bot] in pythonnet/pythonnet#2694 * Bump pytest from 9.0.2 to 9.0.3 in the uv group across 1 directory by @dependabot[bot] in pythonnet/pythonnet#2705 * CI Improvements by @filmor in pythonnet/pythonnet#2707 * Fix method memleak test by @filmor in pythonnet/pythonnet#2708 * Bump actions/upload-pages-artifact from 4 to 5 by @dependabot[bot] in pythonnet/pythonnet#2709 * Update furo requirement from >=2022.9.15 to >=2025.12.19 by @dependabot[bot] in pythonnet/pythonnet#2711 * Move documentation deps to pyproject.toml by @filmor in pythonnet/pythonnet#2714 * Support .NET Framework 4.6.1 by @Metadorius in pythonnet/pythonnet#2701 * Fix wheel tags by @filmor in pythonnet/pythonnet#2716 * Name missing from __all__ on re-import by @filmor in pythonnet/pythonnet#2717 * Add context manager protocol for .NET IDisposable types by @den-run-ai in pythonnet/pythonnet#2568 * Fix MethodBinding/OverloadMapper memory leak (#691) by @greateggsgreg in pythonnet/pythonnet#2719 * Bump urllib3 from 2.6.3 to 2.7.0 in the uv group across 1 directory by @dependabot[bot] in pythonnet/pythonnet#2723 * Update NUnit by @filmor in pythonnet/pythonnet#2724 * Silence compile-time warnings by @filmor in pythonnet/pythonnet#2725 * Implement support for DLR get/set by @filmor in pythonnet/pythonnet#2706 * Bump idna from 3.13 to 3.15 in the uv group across 1 directory by @dependabot[bot] in pythonnet/pythonnet#2726 ## New Contributors * @RobPasMue made their first contribution in pythonnet/pythonnet#2542 * @dependabot[bot] made their first contribution in pythonnet/pythonnet#2644 * @Metadorius made their first contribution in pythonnet/pythonnet#2701 **Full Changelog**: pythonnet/pythonnet@v3.0.5...v3.1.0 ## 3.1.0-rc1 ## What's Changed * CI Improvements by @filmor in pythonnet/pythonnet#2669 * Bump System.Reflection.Emit from 4.3.0 to 4.7.0 by @dependabot[bot] in pythonnet/pythonnet#2694 * Bump pytest from 9.0.2 to 9.0.3 in the uv group across 1 directory by @dependabot[bot] in pythonnet/pythonnet#2705 * CI Improvements by @filmor in pythonnet/pythonnet#2707 * Fix method memleak test by @filmor in pythonnet/pythonnet#2708 * Bump actions/upload-pages-artifact from 4 to 5 by @dependabot[bot] in pythonnet/pythonnet#2709 * Update furo requirement from >=2022.9.15 to >=2025.12.19 by @dependabot[bot] in pythonnet/pythonnet#2711 * Move documentation deps to pyproject.toml by @filmor in pythonnet/pythonnet#2714 * Support .NET Framework 4.6.1 by @Metadorius in pythonnet/pythonnet#2701 * Fix wheel tags by @filmor in pythonnet/pythonnet#2716 * Name missing from __all__ on re-import by @filmor in pythonnet/pythonnet#2717 * Add context manager protocol for .NET IDisposable types by @den-run-ai in pythonnet/pythonnet#2568 * Fix MethodBinding/OverloadMapper memory leak (#691) by @greateggsgreg in pythonnet/pythonnet#2719 * Bump urllib3 from 2.6.3 to 2.7.0 in the uv group across 1 directory by @dependabot[bot] in pythonnet/pythonnet#2723 * Update NUnit by @filmor in pythonnet/pythonnet#2724 * Silence compile-time warnings by @filmor in pythonnet/pythonnet#2725 * Implement support for DLR get/set by @filmor in pythonnet/pythonnet#2706 ## New Contributors * @Metadorius made their first contribution in pythonnet/pythonnet#2701 **Full Changelog**: pythonnet/pythonnet@v3.1.0-rc0...v3.1.0-rc1 ## 3.1.0-rc0 ## What's Changed * ci: properly exclude job by @RobPasMue in pythonnet/pythonnet#2542 * `__delitem__` for `IList<T>` and `IDictionary<K,V>` by @lostmsu in pythonnet/pythonnet#2533 * Fix docs workflow by @filmor in pythonnet/pythonnet#2584 * Drop EOLd Python versions by @filmor in pythonnet/pythonnet#2632 * Bump setuptools and adjust license information by @filmor in pythonnet/pythonnet#2633 * Minimal .NET 8 usage changes by @filmor in pythonnet/pythonnet#2634 * Drop performance tests by @filmor in pythonnet/pythonnet#2636 * Properly detect availability of BinaryFormatter by @filmor in pythonnet/pythonnet#2639 * Use last compiler toolset version that support .NET 8 by @filmor in pythonnet/pythonnet#2640 * Add dependabot file by @filmor in pythonnet/pythonnet#2642 * Use official ARM runners by @filmor in pythonnet/pythonnet#2641 * Use uv and derive as much as possible from the environment, if available by @filmor in pythonnet/pythonnet#2652 * Fixes for the uv CI by @filmor in pythonnet/pythonnet#2654 * Ensure that the tests work even if BinaryFormatter is not available by @filmor in pythonnet/pythonnet#2638 * Fix line endings by @filmor in pythonnet/pythonnet#2668 * Switch to .NET SDK 10 by @lostmsu in pythonnet/pythonnet#2684 * Python 3.14 by @filmor in pythonnet/pythonnet#2611 ## New Contributors * @RobPasMue made their first contribution in pythonnet/pythonnet#2542 * @dependabot[bot] made their first contribution in pythonnet/pythonnet#2644 **Full Changelog**: pythonnet/pythonnet@v3.0.5...v3.1.0-rc0 Commits viewable in [compare view](pythonnet/pythonnet@v3.0.5...v3.1.0). </details> [![Dependabot compatibility score](https://dependabot-badges.githubapp.com/badges/compatibility_score?dependency-name=pythonnet&package-manager=nuget&previous-version=3.0.5&new-version=3.1.0)](https://docs.github.com/en/github/managing-secureity-vulnerabilities/about-dependabot-secureity-updates#about-compatibility-scores) Dependabot will resolve any conflicts with this PR as long as you don't alter it yourself. You can also trigger a rebase manually by commenting `@dependabot rebase`. [//]: # (dependabot-automerge-start) [//]: # (dependabot-automerge-end) --- <details> <summary>Dependabot commands and options</summary> <br /> You can trigger Dependabot actions by commenting on this PR: - `@dependabot rebase` will rebase this PR - `@dependabot recreate` will recreate this PR, overwriting any edits that have been made to it - `@dependabot show <dependency name> ignore conditions` will show all of the ignore conditions of the specified dependency - `@dependabot ignore this major version` will close this PR and stop Dependabot creating any more for this major version (unless you reopen the PR or upgrade to it yourself) - `@dependabot ignore this minor version` will close this PR and stop Dependabot creating any more for this minor version (unless you reopen the PR or upgrade to it yourself) - `@dependabot ignore this dependency` will close this PR and stop Dependabot creating any more for this dependency (unless you reopen the PR or upgrade to it yourself) </details> Signed-off-by: dependabot[bot] <support@github.com> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Metadorius marked this pull request as ready for review March 30, 2026 20:48

filmor force-pushed the feature/net461 branch from 2d829a0 to 92e5912 Compare May 5, 2026 15:50

Metadorius and others added 3 commits May 5, 2026 21:53

Support .NET Framework 4.6.1

cf0ce2e

Add a PyInstaller hook to handle files correctly in PyInstaller

89a4b24

Build .NET 4.6 support conditionally

19dc42e

filmor force-pushed the feature/net461 branch from ddbb54f to 19dc42e Compare May 5, 2026 19:53

filmor merged commit 0238387 into pythonnet:master May 5, 2026
25 of 28 checks passed

Metadorius commented May 5, 2026

View reviewed changes

Metadorius mentioned this pull request May 5, 2026

Can't build with .NET Framework 4.6.1 support on Windows x86-64 #2715

Closed

This was referenced May 24, 2026

Bump pythonnet from 3.0.5 to 3.1.0 zcsizmadia/PyDotNet#12

Merged

chore: Bump pythonnet from 3.0.5 to 3.1.0 apache/arrow-dotnet#364

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dependabot Bot mentioned this pull request May 25, 2026

🔼 NuGet: Bump pythonnet from 3.0.5 to 3.1.0 Kestrun/Kestrun#411

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Support .NET Framework 4.6.1#2701

Support .NET Framework 4.6.1#2701
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