Python 3.9 reached its end-of-life phase on 2025-10-31 (PEP 596).

How to remove support

February 2026

• Update the version in README.md.
• Update various fields in pyproject.toml. (Update project.requires-python to >=3.10 #15402)
• Remove 3.9 from CI and test scripts.
• Update stubtest allow lists. Also check whether items can be moved to the common allow lists. (Remove Python 3.9 stubtest allowlists #15403)
• Remove requires_python >= 3.10 and python_version >= 3.10 from METADATA.toml

May 2026

• Remove 3.9 exclusive branches from stubs.
  • Re-enable ruff codes UP035, UP036 in pyproject.toml.
  • Remove RUF100 code from # noqa directives.
  • Revisit Enable PYI059 #15399.
• Remove obsolete stdlib modules (see VERSIONS).
  • _bootlocale
  • distutils.command.bdist_wininst
  • formatter
  • parser
  • symbol
• Replace typing_extensions imports.
  • ParamSpec
  • TypeAlias
  • TypeGuard
• Remove builtins.ellipsis after type checkers have switched to types.EllipsisType. (See Remove type checker-specific symbols from builtins.pyi and typing.pyi #7580)
• Remove _reader/_writer workarounds in stdlib/_csv.pyi.

(Please amend as necessary.)