Python 3.14 Final Release Candidate Ships: Stable ABI Locked, Launch Set for October

Python 3.14.0rc3 Released – Last Preview Before Stable Launch

Python 3.14.0rc3, the final release candidate for the upcoming Python 3.14 series, is now available for download. This marks the last opportunity for the community to test and prepare for the stable release, scheduled for Tuesday, October 7, 2025.

Learn more about the release process

“This release candidate is essentially the final product. We are now only accepting critical bug fixes, so it’s crucial for maintainers to test their projects and publish wheels,” said Pablo Galindo, Python 3.14 release manager.

Background: A Magic Number Bump and ABI Stability

Python 3.14.0rc3 includes a minor change to the magic number stored in Python bytecode (.pyc) files. This means .pyc files created with rc2 are incompatible and will be recompiled automatically.

However, the Application Binary Interface (ABI) remains unchanged since rc1. Wheels built for any 3.14 release candidate will work with rc3 and future 3.14.x releases, minimizing disruption for package maintainers and users.

This release enters the final phase of the release candidate stage. Only reviewed, clear bug fixes will be allowed between this candidate and the final release. No further ABI changes are anticipated.

What This Means: A Call to Action for the Python Community

Third-party package maintainers should now prepare their projects for Python 3.14. The Python team strongly encourages publishing Python 3.14 wheels on PyPI to facilitate testing and ensure a smooth transition.

“Any binary wheels built against Python 3.14.0 release candidates will work with future versions of Python 3.14,” the release team emphasized. “We need the community to test these wheels and report issues to the Python bug tracker.”

While rc3 is as close to the final release as possible, it remains a preview release and should not be used in production environments.

New Features in Python 3.14

Python 3.14 introduces several major new features compared to 3.13. Key highlights include:

• Free-threaded Python (PEP 779) – officially supported, enabling concurrent execution without the global interpreter lock.
• Deferred annotation evaluation (PEP 649) – improving semantics and performance when using type annotations.
• Template string literals (t-strings, PEP 750) – custom string processing with familiar f-string syntax.
• Multiple interpreters in stdlib (PEP 734) – enabling isolated execution contexts.
• Zstandard compression module (compression.zstd, PEP 784) – support for a modern compression algorithm.
• Omitted brackets in except and except* (PEP 758) – cleaner syntax.
• Syntax highlighting in PyREPL and color support in CLI tools like unittest, argparse, json, and calendar.
• Zero-overhead external debugger interface (PEP 768) – allows debuggers to attach without performance cost.
• UUID versions 6–8 support in the uuid module, with up to 40% faster generation for versions 3–5.
• Disallow return/break/continue that exit a finally block (PEP 765) – preventing common runtime errors.
• Improved C API for configuring Python (PEP 741).
• New interpreter type for certain compilers, providing significantly better performance (opt-in, build from source).
• Improved error messages across the language.
• Builtin HMAC with formally verified implementation.

For the complete list, see the What’s New in Python 3.14 documentation.

Core Developers: Time to Polish Documentation

The release team also reminds core developers to finalize documentation for their changes. Key questions to consider:

1. Are all your changes properly documented?
2. Are they mentioned in What’s New?
3. Have you noticed other changes that lack sufficient documentation?

Python 3.14.0rc3 is available for download from the official Python website. All users and maintainers are urged to test and report issues via the Python bug tracker.