ruff

Breaking changes

What to check before upgrading, taken from the notes of the last 30 releases.

• 0.17.0Oct 9, 2026

  Breaking changes

  • Update the default and latest Python versions for 3.15 (#28792)

  Ruff now defaults to Python 3.11 instead of 3.10 when no Python version is configured through target-version or requires-python. When checking for syntax errors without a configured Python version, Ruff now defaults to Python 3.15 instead of 3.14.

  • Update the default rule set (#28786)

  Several of the flake8-datetimez rules (DTZ001, DTZ005, DTZ006, DTZ007, DTZ011, DTZ012, and DTZ901) are no longer enabled by default, while undefined-local-with-nested-import-star-usage (F406), which corresponds to a syntax error, is now enabled by default.

  • Update Rust crate quick-junit to 0.8.0 (#27295)

  JUnit output now uses a skipped attribute instead of disabled on ` elements and includes a skipped attribute on the root ` element.

  • \[flake8-import-conventions\] Add datetime as dt as a conventional alias (ICN001) (#28790)

  • Support Unicode dummy variable names (#28722)

  The default lint.dummy-variable-rgx now recognizes underscore-prefixed Unicode names, such as _次, as dummy variables.

  • Update to Unicode 17 (#21229, #28784)

  Ruff now uses Unicode 17 data for identifier normalization and named character escapes ("\N{...}").

  • Always show unsafe and display-only fixes in the CLI (#27810)

  The default full output format now shows unsafe fixes and suggestions requiring manual review, regardless of the unsafe-fixes setting. Actually applying unsafe fixes still requires explicit opt-in.

  • Remove the Python dependency from conda-forge builds (conda-forge/ruff-feedstock#361)

  The conda-forge build no longer depends on Python, now supports linux-riscv64, win-arm64, and linux-ppc64le platforms, and now includes shell completions. However, no longer depending on Python means that python -m ruff and import ruff will no longer work. Use ruff directly from PATH instead. PyPI installations and those from the standalone installer are unaffected.

  • Remove support for ruff-lsp (#28750)

  Support for ruff-lsp, the legacy Python language server deprecated in Ruff v0.9.5, has been removed. The Ruff VS Code extension now always uses the native language server; ruff.nativeServer is deprecated and ignored. See the migration guide.

• 0.16.0Jul 23, 2026

  Breaking changes

  • Ruff now enables a much larger set of rules by default (413, up from 59). See the blog post for more details and the new Default Rules page for a full listing of the enabled rules. Note that this is primarily an expansion, but 18 of the more opinionated pycodestyle (E) and pyflakes (F) rules have been removed from the default set: E401, E402, E701, E702, E703, E711, E712, E713, E714, E721, E731, E741, E742, E743, F403, F405, F406, and F722.

  • Ruff can now format Python code blocks in Markdown files and will do this by default. See the documentation for more details.

  • Ruff now supports ruff: ignore comments at the ends of lines, like noqa comments, or on the line preceding a diagnostic. For example, these both suppress an unused-import (F401) diagnostic:

      import math  # ruff: ignore[F401]
  
      # ruff: ignore[F401]
      import os
  

  • Fixes are now shown in check and format --check output:

      ❯ ruff format --check .
      unformatted: File would be reformatted
       --> try.md:1:1
        |
      1 | ```python
        - import   math
      2 + import math
      3 | ```
        |
  
      1 file would be reformatted
  

  This example also shows off the Markdown formatting.

  • format --check now supports the same output formats as the linter, including the github and gitlab outputs for rendering annotations in CI:

      ❯ ruff format --check --output-format github .
      ::error title=ruff (unformatted),file=try.md,line=2,col=8,endLine=2,endColumn=10::try.md:2:8: unformatted: File would be reformatted