v275

• Updated Poetry from 1.8.5 to 2.0.1. (#1734)

v274

• Added a deprecation warning for Python 3.9. (#1732)
• Removed support for Python 3.8. (#1732)
• Improved the error messages shown for EOL or unrecognised major Python versions. (#1732)

v273

• Added more Python project related file and directory names to the list recognised by buildpack detection. (#1729)
• Improved the file listing in the error messages shown when buildpack detection fails or when no Python package manager files are found. (#1728)

v272

• Added a warning if the Python buildpack has been run multiple times in the same build. In January 2025 this warning will be made an error. (#1724)
• Added a warning if an existing .heroku/python/ directory is found in the app source. In January 2025 this warning will be made an error. (#1724)
• Improved the error message shown if the buildpack is used on an unsupported stack. (#1724)
• Fixed Dev Center links to reflect recent article URL changes. (#1723)
• Added metrics for the existence of a uv lockfile. (#1725)

v271

• Updated the Python 3.8 EOL warning message with the new sunset date. (#1721)
• Improved the error message shown when pip install fails due to pip rejecting a package with invalid version metadata. (#1718)
• Improved the error message shown when the copy of pip bundled in the ensurepip module cannot be found. (#1720)

v270

• Changed the default Python version for new apps from 3.12 to 3.13. (#1715)
• Changed Python version pinning behaviour for apps that do not specify a Python version. Repeat builds are now pinned to the major Python version only (3.X) instead of the full Python version (3.X.Y), so that they always use the latest patch version. (#1714)
• Updated Poetry from 1.8.4 to 1.8.5. (#1716)

v269

• The Python 3.13 version alias now resolves to Python 3.13.1. (#1712)
• The Python 3.12 version alias now resolves to Python 3.12.8. (#1712)
• The Python 3.11 version alias now resolves to Python 3.11.11. (#1712)
• The Python 3.10 version alias now resolves to Python 3.10.16. (#1712)
• The Python 3.9 version alias now resolves to Python 3.9.21. (#1712)

v268

• Updated pip from 24.0 to 24.3.1. (#1685)
• Updated wheel from 0.44.0 to 0.45.1. (#1707)

v267

• Deprecated using Pipenv without a lockfile (Pipfile.lock). (#1695)
• Fixed Poetry venv creation when using an outdated Python version whose ensurepip module doesn't enable isolated mode, and the app's build directory contents shadows a package imported by pip (such as brotli). (#1698)

v266

• Added a warning when the files for multiple package managers are found. In the future this warning will become an error. (#1692)
• Updated the build log message shown when installing dependencies to include the package manager command being run. (#1689)
• Changed test dependency installation on Heroku CI to now install requirements.txt and requirements-test.txt in a single pip install invocation rather than separately. This allows pip's resolver to resolve any version conflicts between the two files. (#1689)
• Improved the error messages and buildpack metrics for package manager related failures. (#1689)
• Improved the build log output, error messages and buildpack failure metrics for the NLTK downloader feature. (#1690)