What’s New in Python 3.14 RC3? Key Features, Release Timeline, and Upgrade Tips

Release date: September 18, 2025 (Thursday).

Python 3.14 series is approaching its final version; Python 3.14.0rc3 is the last release candidate.

Important Information

Download: Python 3.14.0rc3

Final release date: October 7, 2025 (Tuesday)

ABI stability: wheel files built from rc1 are compatible with rc2, rc3, and final 3.14.x releases

Warning

This is a "magic" version fixing a bug that requires recompiling .py files created for rc2 before using rc3.

Call to Action

Third‑party Python project maintainers are strongly encouraged to prepare for 3.14, publish wheels on PyPI, and help test other projects.

Python 3.14 Major New Features

New Feature Highlights

PEP 779: Official support for GIL‑free Python

PEP 649: Delayed annotation evaluation, improved semantics

PEP 750: Template string literals (t‑strings) with f‑string‑like syntax

PEP 734: Standard library support for multiple interpreters

PEP 784: Added compression.zstd module for Zstandard compression

PEP 758: except and except* expressions can omit parentheses

PEP 768: Zero‑cost external debugger interface for CPython

UUID improvements: support for versions 6‑8, 40% faster generation for v3‑5

Improved error messages

Built‑in HMAC implementation using verified code from the HACL* project

New CLI tool for inspecting running Python processes

pdb now supports remote attachment to running processes

Build Changes

PEP 761: No longer provide PGP signatures; recommend Sigstore verification

Official binary packages include an experimental JIT compiler (macOS/Windows)

Android binary releases are now available

Documentation Work

Ensure all changes are properly documented

Mention important changes in the "What’s New" section

Check for any other undocumented changes

Installation Management

Windows installer is being replaced by a new installer manager; it can be obtained from the Windows Store or the download page. The traditional installer will continue to be provided throughout the 3.14 and 3.15 series.

Interesting Pi Fact

"The longest time light can fall into a black hole can be described by a complex equation, but the answer is surprisingly simple: 2π times the black hole’s mass. This means π can be defined as half the longest time light spends falling into a black hole!"

Acknowledgements

Thanks to all volunteers who contributed to Python development and these releases; consider supporting the work through volunteering or donating to the Python Software Foundation.

Release Team

Hugo van Kemenade (@hugovk)

Ned Deily (@nad)

Steve Dower (@steve.dower)

Łukasz Langa (@ambv)