Python 3.15.0 alpha 4

This is an early developer preview of Python 3.15

www.python.org/downloads/release/python-3150a4/

Major new features of the 3.15 series, compared to 3.14

Python 3.15 is still in development. This release, 3.15.0a4, is the fourth of seven planned alpha releases.

Alpha releases are intended to make it easier to test the current state of new features and bug fixes and to test the release process.

During the alpha phase, features may be added up until the start of the beta phase (2026-05-05) and, if necessary, may be modified or deleted up until the release candidate phase (2026-07-28). Please keep in mind that this is a preview release and its use is not recommended for production environments.

Many new features for Python 3.15 are still being planned and written. Among the new major new features and changes so far:

• PEP 799: A new high-frequency, low-overhead, statistical sampling profiler and dedicated profiling package
• PEP 686: Python now uses UTF-8 as the default encoding
• PEP 782: A new PyBytesWriter C API to create a Python bytes object
• The JIT compiler has been significantly upgraded, with 3-4% geometric mean performance improvement on x86-64 Linux over the standard interpreter, and 7-8% speedup on AArch64 macOS over the tail-calling interpreter
• Improved error messages
• (Hey, fellow core developer, if a feature you find important is missing from this list, let Hugo know.)

The next pre-release of Python 3.15 will be 3.15.0a5, currently scheduled for 2026-02-10.

More resources

• Online documentation
• PEP 790, 3.15 release schedule
• Report bugs at https://github.com/python/cpython/issues
• Help fund Python directly (or via GitHub Sponsors) and support the Python community

And now for something completely different

Upon this every soul was confounded; for the phenomenon just then observed by Ahab had unaccountably escaped every one else; but its very blinding palpableness must have been the cause.

Thrusting his head half way into the binnacle, Ahab caught one glimpse of the compasses; his uplifted arm slowly fell; for a moment he almost seemed to stagger. Standing behind him Starbuck looked, and lo! the two compasses pointed East, and the Pequod was as infallibly going West.

But ere the first wild alarm could get out abroad among the crew, the old man with a rigid laugh exclaimed, “I have it! It has happened before. Mr. Starbuck, last night’s thunder turned our compasses—that’s all. Thou hast before now heard of such a thing, I take it.”

“Aye; but never before has it happened to me, sir,” said the pale mate, gloomily.

Enjoy the new release

Thanks to all of the many volunteers who help make Python Development and these releases possible! Please consider supporting our efforts by volunteering yourself or through organisation contributions to the Python Software Foundation.

Regards from a snowfully subzero Helsinki,

Your release team,
Hugo van Kemenade
Ned Deily
Steve Dower
Łukasz Langa

Python 3.15.0 alpha 3

This is an early developer preview of Python 3.15

www.python.org/downloads/release/python-3150a3/

Major new features of the 3.15 series, compared to 3.14

Python 3.15 is still in development. This release, 3.15.0a3, is the third of seven planned alpha releases.

Alpha releases are intended to make it easier to test the current state of new features and bug fixes and to test the release process.

During the alpha phase, features may be added up until the start of the beta phase (2026-05-05) and, if necessary, may be modified or deleted up until the release candidate phase (2026-07-28). Please keep in mind that this is a preview release and its use is not recommended for production environments.

Many new features for Python 3.15 are still being planned and written. Among the new major new features and changes so far:

• PEP 799: A new high-frequency, low-overhead, statistical sampling profiler and dedicated profiling package
• PEP 686: Python now uses UTF-8 as the default encoding
• PEP 782: A new PyBytesWriter C API to create a Python bytes object
• Improved error messages
• (Hey, fellow core developer, if a feature you find important is missing from this list, let Hugo know.)

The next pre-release of Python 3.15 will be 3.15.0a4, currently scheduled for 2026-01-13.

More resources

• Online documentation
• PEP 790, 3.15 release schedule
• Report bugs at https://github.com/python/cpython/issues
• Help fund Python directly (or via GitHub Sponsors) and support the Python community

And now for something completely different

Instantly the captain ran forward, and in a loud voice commanded his crew to desist from hoisting the cutting-tackles, and at once cast loose the cables and chains confining the whales to the ship.

“What now?” said the Guernsey-man, when the Captain had returned to them.

“Why, let me see; yes, you may as well tell him now that—that—in fact, tell him I’ve diddled him, and (aside to himself) perhaps somebody else.”

Enjoy the new release

Thanks to all of the many volunteers who help make Python Development and these releases possible! Please consider supporting our efforts by volunteering yourself or through organisation contributions to the Python Software Foundation.

Regards from an even deeper darker Helsinki,

Your release team,
Hugo van Kemenade
Ned Deily
Steve Dower
Łukasz Langa

Python 3.14.2 and 3.13.11 are now available!

Two more, just three days after the last? Yes!

We found some regressions, so here’s an expedited pair of releases. They also come with some bonus security fixes.

Python 3.14.2

www.python.org/downloads/release/python-3142/

Python 3.14.2 is the second maintenance release of 3.14, containing 18 bugfixes, build improvements and documentation changes since 3.14.1.

This is an expedited release to fix the following regressions:

• gh-142206: Exceptions in multiprocessing in running programs while upgrading Python.

• gh-142214: Exceptions in dataclasses without __init__ method.

• gh-142218: Segmentation faults and assertion failures in insertdict.

• gh-140797: Crash when using multiple capturing groups in re.Scanner

And these security fixes:

• gh-142145: Remove quadratic behavior in node ID cache clearing (CVE-2025-12084)

• gh-119452: Fix a potential virtual memory allocation denial of service in http.server

See the full changelog.

Python 3.13.11

www.python.org/downloads/release/python-31311/

Python 3.13.11 is the eleventh maintenance release of 3.13. This is an expedited release to fix the following regressions:

• gh-142206: Exceptions in multiprocessing in running programs while upgrading Python.

• gh-142218: Segmentation faults and assertion failures in insertdict.

• gh-140797: Crash when using multiple capturing groups in re.Scanner

And these security fixes:

• gh-142145: Remove quadratic behavior in node ID cache clearing (CVE-2025-12084)

• gh-119451: Fix a potential denial of service in http.client

• gh-119452: Fix a potential virtual memory allocation denial of service in http.server

See the full changelog.

Enjoy the new release

Thanks to all of the many volunteers who help make Python Development and these releases possible! Please consider supporting our efforts by volunteering yourself or through organisation contributions to the Python Software Foundation.

Regards from deeper darker Helsinki,

Your release team,
Hugo van Kemenade
Thomas Wouters
Ned Deily
Steve Dower
Łukasz Langa

Python 3.13.10 is now available, too, you know!

The latest version of Python 3.13 is now available!

Python 3.13.10

 

https://www.python.org/downloads/release/python-31310/

This is the tenth maintenance release of Python 3.13

Python 3.13.10 is the tenth maintenance release of 3.13, containing around 300 bugfixes, build improvements and documentation changes since 3.13.9.

Full Changelog

More resources

• Online Documentation
• PEP 719, 3.13 Release Schedule
• Report bugs at https://github.com/python/cpython/issues.
• Help fund Python directly (or via GitHub Sponsors), and support the Python community.

 

Enjoy the new releases

Thanks to all of the many volunteers who help make Python Development and these releases possible! Please consider supporting our efforts by volunteering yourself or through organization contributions to the Python Software Foundation.

Regards from your package managers,

Thomas Wouters
Ned Deily
Steve Dower
Łukasz Langa

Python 3.14.1 is now available!

This is first maintenance release of Python 3.14

Python 3.14.1 is the first maintenance release of 3.14, containing around 558 bugfixes, build improvements and documentation changes since 3.14.0.

Major new features of the 3.14 series, compared to 3.13

Some of the major new features and changes in Python 3.14 are:

New features

• PEP 779: Free-threaded Python is officially supported
• PEP 649: The evaluation of annotations is now deferred, improving the semantics of using annotations.
• PEP 750: Template string literals (t-strings) for custom string processing, using the familiar syntax of f-strings.
• PEP 734: Multiple interpreters in the stdlib.
• PEP 784: A new module compression.zstd providing support for the Zstandard compression algorithm.
• PEP 758: except and except* expressions may now omit the brackets.
• Syntax highlighting in PyREPL, and support for color in unittest, argparse, json and calendar CLIs.
• PEP 768: A zero-overhead external debugger interface for CPython.
• UUID versions 6-8 are now supported by the uuid module, and generation of versions 3-5 are up to 40% faster.
• PEP 765: Disallow return/break/continue that exit a finally block.
• PEP 741: An improved C API for configuring Python.
• A new type of interpreter. For certain newer compilers, this interpreter provides significantly better performance. Opt-in for now, requires building from source.
• Improved error messages.
• Builtin implementation of HMAC with formally verified code from the HACL* project.
• A new command-line interface to inspect running Python processes using asynchronous tasks.
• The pdb module now supports remote attaching to a running Python process.

For more details on the changes to Python 3.14, see What’s new in Python 3.14.

Build changes

• PEP 761: Python 3.14 and onwards no longer provides PGP signatures for release artifacts. Instead, Sigstore is recommended for verifiers.
• Official macOS and Windows release binaries include an experimental JIT compiler.
• Official Android binary releases are now available.

Incompatible changes, removals and new deprecations

• Incompatible changes
• Python removals and deprecations
• C API removals and deprecations
• Overview of all pending deprecations

Python install manager

The installer we offer for Windows is being replaced by our new install manager, which can be installed from the Windows Store or from its download page. See our documentation for more information. The JSON file available for download contains the list of all the installable packages available as part of this release, including file URLs and hashes, but is not required to install the latest release. The traditional installer will remain available throughout the 3.14 and 3.15 releases.

More resources

• Online documentation
• PEP 745, 3.14 Release Schedule
• Report bugs at github.com/python/cpython/issues
• Help fund Python directly (or via GitHub Sponsors) and support the Python community

And now for something completely different

Seki Takakazu (関 孝和; c. March 1642 – December 5, 1708) was a Japanese mathematician and samurai who laid the foundations of Japanese mathematics, later known as wasan (和算, from wa (“Japanese”) and san (“calculation”).

Seki was a contemporary of Isaac Newton and Gottfried Leibniz but worked independently. He created a new algebraic system, worked on infinitesimal calculus, and is credited with the discovery of Bernoulli numbers (before Bernoulli’s birth).

Seki also calculated π to 11 decimal places using a polygon with 131,072 sides inscribed within a circle, using an acceleration method now known as Aitken’s delta-squared process, which was rediscovered by Alexander Aitken in 1926.

Enjoy the new release

Thanks to all of the many volunteers who help make Python Development and these releases possible! Please consider supporting our efforts by volunteering yourself or through organisation contributions to the Python Software Foundation.

Regards from deepest darkest Helsinki,

Your release team,
Hugo van Kemenade
Ned Deily
Steve Dower
Łukasz Langa

Python 3.15.0 alpha 2

This is an early developer preview of Python 3.15

https://www.python.org/downloads/release/python-3150a2/

Major new features of the 3.15 series, compared to 3.14

Python 3.15 is still in development. This release, 3.15.0a2, is the second of seven planned alpha releases.

Alpha releases are intended to make it easier to test the current state of new features and bug fixes and to test the release process.

During the alpha phase, features may be added up until the start of the beta phase (2026-05-05) and, if necessary, may be modified or deleted up until the release candidate phase (2026-07-28). Please keep in mind that this is a preview release and its use is not recommended for production environments.

Many new features for Python 3.15 are still being planned and written. Among the new major new features and changes so far:

• PEP 799: A new high-frequency, low-overhead, statistical sampling profiler and dedicated profiling package
• PEP 686: Python now uses UTF-8 as the default encoding
• PEP 782: A new PyBytesWriter C API to create a Python bytes object
• Improved error messages
• (Hey, fellow core developer, if a feature you find important is missing from this list, let Hugo know.)

The next pre-release of Python 3.15 will be 3.15.0a3, currently scheduled for 2025-12-16.

More resources

• Online documentation
• PEP 790, 3.15 release schedule
• Report bugs at https://github.com/python/cpython/issues
• Help fund Python directly (or via GitHub Sponsors) and support the Python community

And now for something completely different

“An hour,” said Ahab, standing rooted in his boat’s stern; and he gazed beyond the whale’s place, towards the dim blue spaces and wide wooing vacancies to leeward. It was only an instant; for again his eyes seemed whirling round in his head as he swept the watery circle. The breeze now freshened; the sea began to swell.

“The birds!—the birds!” cried Tashtego.

Enjoy the new release

Thanks to all of the many volunteers who help make Python Development and these releases possible! Please consider supporting our efforts by volunteering yourself or through organisation contributions to the Python Software Foundation.

Regards from a crisp and sunny subzero Helsinki,

Your release team,
Hugo van Kemenade
Ned Deily
Steve Dower
Łukasz Langa

Python 3.15.0 alpha 1

This is an early developer preview of Python 3.15

https://www.python.org/downloads/release/python-3150a1/

Major new features of the 3.15 series, compared to 3.14

Python 3.15 is still in development. This release, 3.15.0a1, is the first of seven planned alpha releases.

Alpha releases are intended to make it easier to test the current state of new features and bug fixes and to test the release process.

During the alpha phase, features may be added up until the start of the beta phase (2026-05-05) and, if necessary, may be modified or deleted up until the release candidate phase (2026-07-28). Please keep in mind that this is a preview release and its use is not recommended for production environments.

Many new features for Python 3.15 are still being planned and written. Among the new major new features and changes so far:

• PEP 799: A dedicated profiling package for Python profiling tools
• PEP 686: Python now uses UTF-8 as the default encoding
• PEP 782: A new PyBytesWriter C API to create a Python bytes object
• Improved error messages
• (Hey, fellow core developer, if a feature you find important is missing from this list, let Hugo know.)

The next pre-release of Python 3.15 will be 3.15.0a2, currently scheduled for 2025-11-18.

More resources

• Online documentation
• PEP 790, 3.15 Release Schedule
• Report bugs at https://github.com/python/cpython/issues
• Help fund Python directly (or via GitHub Sponsors) and support the Python community

And now for something completely different

And hence not only at substantiated times, upon well known separate feeding-grounds, could Ahab hope to encounter his prey; but in crossing the widest expanses of water between those grounds he could, by his art, so place and time himself on his way, as even then not to be wholly without prospect of a meeting.

Enjoy the new release

Thanks to all of the many volunteers who help make Python Development and these releases possible! Please consider supporting our efforts by volunteering yourself or through organisation contributions to the Python Software Foundation.

Regards from Helsinki before the first PyCon Finland in 9 years,

Your release team,
Hugo van Kemenade
Ned Deily
Steve Dower
Łukasz Langa