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Upgrading ruff 0.8 to 0.9

Breaking0.8.6 → 0.9.10Breaking3Deprecated1New50Changed82Fixed101Other21

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BreakingUpgrade verdict

3 breaking changes.

In plain terms
  • The code formatter now follows a new style guide, so running it may reformat your code differently than before.
  • The pyupgrade rule that modernized Union and Optional is split into two rules, so Optional issues now report under UP045.
  • The rule formerly known as RUF025 is now identified as RUF037.
  • Adds a deprecation warning for ruff-lsp related settings.
Must act 4 items need code or config changes

What you must change

Breaking3
Ruff now formats code according to the 2025 style guide, so formatting output may differ.
0.9.0GitHub ReleaseSummarizedView source
Splits UP007 into UP007 for Union and new UP045 for Optional.
UP007UP045UnionOptional
0.9.0GitHub ReleaseSummarizedView source
Recodes RUF025 to RUF037.
RUF025RUF037
0.9.0GitHub ReleaseSummarizedView source

Deprecations to plan for

Deprecated1
Adds a deprecation warning for ruff-lsp related settings.
ruff-lsp
0.9.5GitHub ReleaseSummarizedView source