Python 3.14.3 and 3.13.12 Roll Out With Critical Bug Fixes, New Features

Breaking News: Python 3.14.3 and 3.13.12 Released

March 3, 2025 — The Python Software Foundation has released Python 3.14.3, the third maintenance update for the 3.14 series, alongside a corresponding patch for version 3.13.12. The updates address over 299 bug fixes, build improvements, and documentation refinements since the previous release.

"This release ensures stability for the 3.14 branch while incorporating important security patches," said Thomas Wouters, Python Release Manager. "We encourage all users to upgrade as soon as possible."

The release of 3.13.12 similarly targets critical issues in the older stable line. Both versions are available for download from the official Python website.

Key Features in Python 3.14 Series

Python 3.14 introduced several major features that are now fully available in the maintenance releases:

• Free-threaded Python (PEP 779): Officially supported, allowing parallel execution without the Global Interpreter Lock.
• Deferred annotation evaluation (PEP 649): Improves semantics when using annotations, reducing forward-reference issues.
• Template string literals (t-strings) (PEP 750): Custom string processing with familiar f-string syntax.
• Multiple interpreters in stdlib (PEP 734): Enables isolated subinterpreters.
• Zstandard compression (PEP 784): New compression.zstd module.
• Modified exception syntax (PEP 758): Brackets optional in except and except* expressions.
• Enhanced CLI colors: Syntax highlighting in PyREPL, support in unittest, argparse, json, calendar.
• External debugger interface (PEP 768): Zero-overhead debugging for CPython.
• UUID versions 6-8: New support plus performance boost for versions 3-5.
• Improved error messages and a new interpreter type for newer compilers (opt-in).

Background

Python releases follow a predictable cadence: feature releases (e.g., 3.14.0) introduce new capabilities, while maintenance releases (3.14.1, 3.14.2, etc.) focus on stability. Python 3.14.3 is the third such update, providing a cumulative patch for bugs discovered since the previous maintenance release.

This update also marks changes in the release infrastructure: starting with Python 3.14, PGP signatures are no longer provided. Instead, the project recommends Sigstore for verifying artifact integrity (PEP 761). Additionally, official macOS and Windows binaries now include an experimental JIT compiler.

What This Means

For developers and system administrators, upgrading to 3.14.3 (or 3.13.12 for those on the 3.13 branch) is recommended to resolve known issues and incorporate security improvements. The 3.14 series brings significant advancements like free-threaded execution and deferred annotations, which are now considered stable in this maintenance release.

Notable deprecations and removals affect code relying on older behaviors. Users should review the list of incompatible changes in the official documentation. The Python install manager for Windows has also been updated, offering a new installer via the Windows Store.

Incompatible Changes and Deprecations

The release includes several backwards-incompatible changes, such as disallowing return/break/continue that exit a finally block (PEP 765). Additionally, various C API items have been removed or deprecated.

For a complete overview, consult the "What's New in Python 3.14" guide.

— Python Software Foundation