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fix: load .NET assemblies when running on .NET 9+ - #174
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GitHub-hosted runners now ship .NET 8, 9 and 10. clr_loader 0.2.x (used
with pythonnet 3.0.x, e.g. on Python 3.9) picks the runtime by string
sort, so it selects .NET 9. On .NET 9+, pythonnet 3.0.x's
clr.AddReference("<abs path>.dll") parses the path as an assembly name
and throws FileNotFoundException before its full-path fallback runs. The
error was swallowed, so imports failed with
"No module named 'Microsoft.Azure'".
Pass the path without the ".dll" suffix so pythonnet probes and loads
"<path>.dll" directly, which works on .NET 8, 9 and 10 with pythonnet
3.0.x and 3.1.x.
Also pin the e2e matrix to Python 3.13 instead of '3.x', which now
resolves to 3.14 and is outside requires-python (<3.14).
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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Yennifer Santos (ydaponte)
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Sep 24, 2026
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LGTM!
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Summary
Fixes the
ci / buildfailure seen on everyCI/CDPR run since January 2026 (including #173, #167, #168 and #171).Root cause
GitHub-hosted runners now have .NET 8, 9 and 10 installed.
poetry.lock, and what Python 3.9 installs), runtimes are sorted by version string, so"9.0.x"beats"8.0.x"and"10.0.x". The evaluator therefore runs on .NET 9.clr.AddReference("/abs/path/Foo.dll")in pythonnet 3.0.x parses the path as an assembly name and throwsFileNotFoundExceptionbefore its full-path fallback runs.load_dotnet_assemblies()swallows that exception, so the tests fail later withModuleNotFoundError: No module named 'Microsoft.Azure'.This affects users too, not just CI: anyone on Python 3.9 (or with pythonnet 3.0.x pinned) who has .NET 9 installed next to .NET 8 hits the same error.
Changes
_pythonnet/__init__.py: pass the assembly path without the.dllsuffix. pythonnet then probes and loads<path>.dlldirectly, which works on .NET 8, 9 and 10 with pythonnet 3.0.x and 3.1.x.ci.yml: pin the e2e matrix to3.13instead of3.x.3.xnow resolves to Python 3.14, whichrequires-python = ">=3.9,<3.14"rejects, so the e2e jobs would fail as soon asbuildis green.Validation (local, with .NET 8.0 + 9.0 + 10.0 runtimes installed like the runners)
pre-commit run --all-filesNo module named 'Microsoft.Azure'pytest examplesWindows was not tested locally.
After this merges, #173 (action pinning) should go green on a rebase / re-run. It touches different lines of
ci.yml, so there's no conflict.