Python infos

Python core development news and information.

  • Python 3.15.0 alpha 5 (yes, another alpha!)

    Note: 3.14.0a4 was accidentally built against main from 2025-12-23 instead of 2026-01-13, so this 3.14.0a5 is an extra release correctly built against 2026-01-14.

    This is an early developer preview of Python 3.15

    www.python.org/downloads/release/python-3150a5/

    Major new features of the 3.15 series, compared to 3.14

    Python 3.15 is still in development. This release, 3.15.0a5, is the fifth of seven eight 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 4-5% 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 3.15.0a6, currently scheduled for 2026-02-10.

    More resources

    And now for something completely different

    At last it was given out that some time next day the ship would certainly sail. So next morning, Queequeg and I took a very early start.

    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 still snowfully subzero Helsinki,

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

  • Python 3.15.0 alpha 4

    Edit: This 3.14.0a4 was accidentally built against `main` from 2025-12-23 instead of 2026-01-13, so 3.14.0a5 is an extra release correctly built against 2026-01-14.

    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

    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

    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

    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

     

    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!

    Two snakes enjoying a pie with 3.14 on the top and π crimping

    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

    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

    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

    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

  • Python 3.13.9 is now available!

     

    Python 3.13.9

     
     
    3.13.9 is an expedited release containing a fix for one specific regression in Python 3.13.8:
    • gh-139783: Fix inspect.getsourcelines for the case when a decorator is followed by a comment or an empty line.

    There are no other changes in this release, compared to 3.13.8.

    More resources

      

    Enjoy the new releases

     

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

    Your expedited release team,
    Your release team,
    Thomas Wouters
    Ned Deily
    Steve Dower
    Łukasz Langa

  • Python 3.12.12, 3.11.14, 3.10.19 and 3.9.24 are now available!

     

    Old-timer Release Party

    We couldn’t just let Hugo have fun with 3.14.0, so here are new security releases of the venerated Python versions, 3.12 through 3.9!

    Security content in these releases

     

    XML-related

    Archive-related

    • gh-130577: tarfile now validates archives to ensure member offsets are non-negative.
    • gh-139700: Now checking consistency of the zip64 end of central directory record. Added support for records with “zip64 extensible data” if there are no bytes prepended to the ZIP file.

    HTML parsing-related

    • gh-135661: Fixed parsing start and end tags in html.parser.HTMLParser according to the HTML5 standard.
    • Whitespaces no longer accepted between </ and the tag name. E.g. </ script> does not end the script section.
    • Vertical tabulation (\v) and non-ASCII whitespaces no longer recognized as whitespaces. The only whitespaces are \t\n\r\f and space.
    • Null character (U+0000) no longer ends the tag name.
    • Attributes and slashes after the tag name in end tags are now ignored, instead of terminating after the first > in quoted attribute value. E.g. </script/foo=">"/>.
    • Multiple slashes and whitespaces between the last attribute and closing > are now ignored in both start and end tags. E.g. <a foo=bar/ //>.
    • Multiple = between attribute name and value are no longer collapsed. E.g. <a foo==bar> produces attribute “foo” with value “=bar”.
    • gh-135661: Fixed CDATA section parsing in html.parser.HTMLParser according to the HTML5 standard: ] ]> and ]] > no longer end the CDATA section. Add private method _set_support_cdata() which can be used to specify how to parse <[CDATA[ — as a CDATA section in foreign content (SVG or MathML) or as a bogus comment in the HTML namespace.
    • gh-102555: Fixed comment parsing in html.parser.HTMLParser according to the HTML5 standard. --!> now ends the comment. -- > no longer ends the comment. Support abnormally ended empty comments <--> and <--->.
    • gh-135462: Fixed quadratic complexity in processing specially crafted input in html.parser.HTMLParser. End-of-file errors are now handled according to the HTML5 specs – comments and declarations are automatically closed, tags are ignored.
    • gh-118350: Fixed support of escapable raw text mode (elements “textarea” and “title”) in html.parser.HTMLParser.
    • gh-86155: html.parser.HTMLParser.close() no longer loses data when the <script> tag is not closed.

     

    Python 3.12.12


    Python 3.11.14

    Additional security content in this release:


    Python 3.10.19

    Additional security content in this release:


    Python 3.9.24

    Additional security content in this release:


    Stay safe and upgrade!

    As always, upgrading is highly recommended to all users of affected versions.

    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 very old tireless release team,
    Thomas Wouters
    Pablo Galindo Salgado
    Łukasz Langa
    Ned Deily
    Steve Dower

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