3.13.rst

What's New In Python 3.13

Editor:	TBD

This article explains the new features in Python 3.13, compared to 3.12.

For full details, see the :ref:`changelog <changelog>`.

Note

Prerelease users should be aware that this document is currently in draft form. It will be updated substantially as Python 3.13 moves towards release, so it's worth checking back even after reading earlier versions.

Summary -- Release highlights

Important deprecations, removals or restrictions:

• :ref:`PEP 594 <whatsnew313-pep594>`: The remaining 19 "dead batteries" have been removed from the standard library: :mod:`!aifc`, :mod:`!audioop`, :mod:`!cgi`, :mod:`!cgitb`, :mod:`!chunk`, :mod:`!crypt`, :mod:`!imghdr`, :mod:`!mailcap`, :mod:`!msilib`, :mod:`!nis`, :mod:`!nntplib`, :mod:`!ossaudiodev`, :mod:`!pipes`, :mod:`!sndhdr`, :mod:`!spwd`, :mod:`!sunau`, :mod:`!telnetlib`, :mod:`!uu` and :mod:`!xdrlib`.
• PEP 602 ("Annual Release Cycle for Python") has been updated:
  • Python 3.9 - 3.12 have one and a half years of full support, followed by three and a half years of security fixes.
  • Python 3.13 and later have two years of full support, followed by three years of security fixes.

New Features

Other Language Changes

• Allow the count argument of :meth:`str.replace` to be a keyword. (Contributed by Hugo van Kemenade in :gh:`106487`.)
• Compiler now strip indents from docstrings. This will reduce the size of :term:`bytecode cache <bytecode>` (e.g. .pyc file). For example, cache file size for sqlalchemy.orm.session in SQLAlchemy 2.0 is reduced by about 5%. This change will affect tools using docstrings, like :mod:`doctest`. (Contributed by Inada Naoki in :gh:`81283`.)
• The :func:`compile` built-in can now accept a new flag, ast.PyCF_OPTIMIZED_AST, which is similar to ast.PyCF_ONLY_AST except that the returned AST is optimized according to the value of the optimize argument. (Contributed by Irit Katriel in :gh:`108113`).
• :mod:`multiprocessing`, :mod:`concurrent.futures`, :mod:`compileall`: Replace :func:`os.cpu_count` with :func:`os.process_cpu_count` to select the default number of worker threads and processes. Get the CPU affinity if supported. (Contributed by Victor Stinner in :gh:`109649`.)
• :func:`os.path.realpath` now resolves MS-DOS style file names even if the file is not accessible. (Contributed by Moonsik Park in :gh:`82367`.)
• Fixed a bug where a :keyword:`global` declaration in an :keyword:`except` block is rejected when the global is used in the :keyword:`else` block. (Contributed by Irit Katriel in :gh:`111123`.)
• Added a new environment variable :envvar:`PYTHON_FROZEN_MODULES`. It determines whether or not frozen modules are ignored by the import machinery, equivalent of the :option:`-X frozen_modules <-X>` command-line option. (Contributed by Yilei Yang in :gh:`111374`.)

New Modules

• None yet.

Improved Modules

ast

• :func:`ast.parse` now accepts an optional argument optimize which is passed on to the :func:`compile` built-in. This makes it possible to obtain an optimized AST. (Contributed by Irit Katriel in :gh:`108113`).

array

• Add 'w' type code (Py_UCS4) that can be used for Unicode strings. It can be used instead of 'u' type code, which is deprecated. (Contributed by Inada Naoki in :gh:`80480`.)

copy

• Add :func:`copy.replace` function which allows to create a modified copy of an object, which is especially useful for immutable objects. It supports named tuples created with the factory function :func:`collections.namedtuple`, :class:`~dataclasses.dataclass` instances, various :mod:`datetime` objects, :class:`~inspect.Signature` objects, :class:`~inspect.Parameter` objects, :ref:`code object <code-objects>`, and any user classes which define the :meth:`!__replace__` method. (Contributed by Serhiy Storchaka in :gh:`108751`.)

dbm

• Add :meth:`dbm.gnu.gdbm.clear` and :meth:`dbm.ndbm.ndbm.clear` methods that remove all items from the database. (Contributed by Donghee Na in :gh:`107122`.)

doctest

• The :meth:`doctest.DocTestRunner.run` method now counts the number of skipped tests. Add :attr:`doctest.DocTestRunner.skips` and :attr:`doctest.TestResults.skipped` attributes. (Contributed by Victor Stinner in :gh:`108794`.)

io

The :class:`io.IOBase` finalizer now logs the close() method errors with :data:`sys.unraisablehook`. Previously, errors were ignored silently by default, and only logged in :ref:`Python Development Mode <devmode>` or on :ref:`Python built on debug mode <debug-build>`. (Contributed by Victor Stinner in :gh:`62948`.)

opcode

• Move opcode.ENABLE_SPECIALIZATION to _opcode.ENABLE_SPECIALIZATION. This field was added in 3.12, it was never documented and is not intended for external usage. (Contributed by Irit Katriel in :gh:`105481`.)
• Removed opcode.is_pseudo, opcode.MIN_PSEUDO_OPCODE and opcode.MAX_PSEUDO_OPCODE, which were added in 3.12, were never documented or exposed through dis, and were not intended to be used externally.

os

• Add :func:`os.process_cpu_count` function to get the number of logical CPUs usable by the calling thread of the current process. (Contributed by Victor Stinner in :gh:`109649`.)
• Add a low level interface for Linux's timer notification file descriptors via :func:`os.timerfd_create`, :func:`os.timerfd_settime`, :func:`os.timerfd_settime_ns`, :func:`os.timerfd_gettime`, and :func:`os.timerfd_gettime_ns`, :const:`os.TFD_NONBLOCK`, :const:`os.TFD_CLOEXEC`, :const:`os.TFD_TIMER_ABSTIME`, and :const:`os.TFD_TIMER_CANCEL_ON_SET` (Contributed by Masaru Tsuchiyama in :gh:`108277`.)
• :func:`os.cpu_count` and :func:`os.process_cpu_count` can be overridden through the new environment variable :envvar:`PYTHON_CPU_COUNT` or the new command-line option :option:`-X cpu_count <-X>`. This option is useful for users who need to limit CPU resources of a container system without having to modify the container (application code). (Contributed by Donghee Na in :gh:`109595`)

pathlib

• Add :exc:`pathlib.UnsupportedOperation`, which is raised instead of :exc:`NotImplementedError` when a path operation isn't supported. (Contributed by Barney Gale in :gh:`89812`.)
• Add :meth:`pathlib.Path.from_uri`, a new constructor to create a :class:`pathlib.Path` object from a 'file' URI (file:/). (Contributed by Barney Gale in :gh:`107465`.)
• Add support for recursive wildcards in :meth:`pathlib.PurePath.match`. (Contributed by Barney Gale in :gh:`73435`.)
• Add follow_symlinks keyword-only argument to :meth:`pathlib.Path.glob`, :meth:`~pathlib.Path.rglob`, :meth:`~pathlib.Path.is_file`, and :meth:`~pathlib.Path.is_dir`. (Contributed by Barney Gale in :gh:`77609` and :gh:`105793`.)

pdb

• Add ability to move between chained exceptions during post mortem debugging in :func:`~pdb.pm` using the new exceptions [exc_number] command for Pdb. (Contributed by Matthias Bussonnier in :gh:`106676`.)
• Expressions/Statements whose prefix is a pdb command are now correctly identified and executed. (Contributed by Tian Gao in :gh:`108464`.)

sqlite3

• A :exc:`ResourceWarning` is now emitted if a :class:`sqlite3.Connection` object is not :meth:`closed <sqlite3.Connection.close>` explicitly. (Contributed by Erlend E. Aasland in :gh:`105539`.)

tkinter

• Add :mod:`tkinter` widget methods: :meth:`!tk_busy_hold`, :meth:`!tk_busy_configure`, :meth:`!tk_busy_cget`, :meth:`!tk_busy_forget`, :meth:`!tk_busy_current`, and :meth:`!tk_busy_status`. (Contributed by Miguel, klappnase and Serhiy Storchaka in :gh:`72684`.)

traceback

• Add show_group parameter to :func:`traceback.TracebackException.format_exception_only` to format the nested exceptions of a :exc:`BaseExceptionGroup` instance, recursively. (Contributed by Irit Katriel in :gh:`105292`.)

typing

• Add :func:`typing.get_protocol_members` to return the set of members defining a :class:`typing.Protocol`. Add :func:`typing.is_protocol` to check whether a class is a :class:`typing.Protocol`. (Contributed by Jelle Zijlstra in :gh:`104873`.)

venv

• Add support for adding source control management (SCM) ignore files to a virtual environment's directory. By default, Git is supported. This is implemented as opt-in via the API which can be extended to support other SCMs (:class:`venv.EnvBuilder` and :func:`venv.create`), and opt-out via the CLI (using --without-scm-ignore-files). (Contributed by Brett Cannon in :gh:`108125`.)

Optimizations

• :func:`textwrap.indent` is now ~30% faster than before for large input. (Contributed by Inada Naoki in :gh:`107369`.)

Deprecated

• :mod:`array`: :mod:`array`'s 'u' format code, deprecated in docs since Python 3.3, emits :exc:`DeprecationWarning` since 3.13 and will be removed in Python 3.16. Use the 'w' format code instead. (contributed by Hugo van Kemenade in :gh:`80480`)

• :mod:`ctypes`: Deprecate undocumented :func:`!ctypes.SetPointerType` and :func:`!ctypes.ARRAY` functions. Replace ctypes.ARRAY(item_type, size) with item_type * size. (Contributed by Victor Stinner in :gh:`105733`.)

• :mod:`getopt` and :mod:`optparse` modules: They are now :term:`soft deprecated`: the :mod:`argparse` should be used for new projects. Previously, the :mod:`optparse` module was already deprecated, its removal was not scheduled, and no warnings was emitted: so there is no change in practice. (Contributed by Victor Stinner in :gh:`106535`.)

• :mod:`http.server`: :class:`http.server.CGIHTTPRequestHandler` now emits a :exc:`DeprecationWarning` as it will be removed in 3.15. Process based CGI http servers have been out of favor for a very long time. This code was outdated, unmaintained, and rarely used. It has a high potential for both security and functionality bugs. This includes removal of the --cgi flag to the python -m http.server command line in 3.15.

• :mod:`typing`:

  • Creating a :class:`typing.NamedTuple` class using keyword arguments to denote the fields (NT = NamedTuple("NT", x=int, y=int)) is deprecated, and will be disallowed in Python 3.15. Use the class-based syntax or the functional syntax instead. (Contributed by Alex Waygood in :gh:`105566`.)
  • When using the functional syntax to create a :class:`typing.NamedTuple` class or a :class:`typing.TypedDict` class, failing to pass a value to the 'fields' parameter (NT = NamedTuple("NT") or TD = TypedDict("TD")) is deprecated. Passing None to the 'fields' parameter (NT = NamedTuple("NT", None) or TD = TypedDict("TD", None)) is also deprecated. Both will be disallowed in Python 3.15. To create a NamedTuple class with 0 fields, use class NT(NamedTuple): pass or NT = NamedTuple("NT", []). To create a TypedDict class with 0 fields, use class TD(TypedDict): pass or TD = TypedDict("TD", {}). (Contributed by Alex Waygood in :gh:`105566` and :gh:`105570`.)
  • :func:`typing.no_type_check_decorator` is deprecated, and scheduled for removal in Python 3.15. After eight years in the :mod:`typing` module, it has yet to be supported by any major type checkers. (Contributed by Alex Waygood in :gh:`106309`.)
  • :data:`typing.AnyStr` is deprecated. In Python 3.16, it will be removed from typing.__all__, and a :exc:`DeprecationWarning` will be emitted when it is imported or accessed. It will be removed entirely in Python 3.18. Use the new :ref:`type parameter syntax <type-params>` instead. (Contributed by Michael The in :gh:`107116`.)

• :mod:`wave`: Deprecate the getmark(), setmark() and getmarkers() methods of the :class:`wave.Wave_read` and :class:`wave.Wave_write` classes. They will be removed in Python 3.15. (Contributed by Victor Stinner in :gh:`105096`.)

• Passing more than one positional argument to :func:`sqlite3.connect` and the :class:`sqlite3.Connection` constructor is deprecated. The remaining parameters will become keyword-only in Python 3.15.

  Deprecate passing name, number of arguments, and the callable as keyword arguments, for the following :class:`sqlite3.Connection` APIs:

  • :meth:`~sqlite3.Connection.create_function`
  • :meth:`~sqlite3.Connection.create_aggregate`

  Deprecate passing the callback callable by keyword for the following :class:`sqlite3.Connection` APIs:

  • :meth:`~sqlite3.Connection.set_authorizer`
  • :meth:`~sqlite3.Connection.set_progress_handler`
  • :meth:`~sqlite3.Connection.set_trace_callback`

  The affected parameters will become positional-only in Python 3.15.

  (Contributed by Erlend E. Aasland in :gh:`107948` and :gh:`108278`.)

• The dis.HAVE_ARGUMENT separator is deprecated. Check membership in :data:`~dis.hasarg` instead. (Contributed by Irit Katriel in :gh:`109319`.)

• Deprecate non-standard format specifier "N" for :class:`decimal.Decimal`. It was not documented and only supported in the C implementation. (Contributed by Serhiy Storchaka in :gh:`89902`.)

• Emit deprecation warning for non-integer numbers in :mod:`gettext` functions and methods that consider plural forms even if the translation was not found. (Contributed by Serhiy Storchaka in :gh:`88434`.)

Pending Removal in Python 3.14

• :mod:`argparse`: The type, choices, and metavar parameters of :class:`!argparse.BooleanOptionalAction` are deprecated and will be removed in 3.14. (Contributed by Nikita Sobolev in :gh:`92248`.)

• :mod:`ast`: The following features have been deprecated in documentation since Python 3.8, now cause a :exc:`DeprecationWarning` to be emitted at runtime when they are accessed or used, and will be removed in Python 3.14:

  • :class:`!ast.Num`
  • :class:`!ast.Str`
  • :class:`!ast.Bytes`
  • :class:`!ast.NameConstant`
  • :class:`!ast.Ellipsis`

  Use :class:`ast.Constant` instead. (Contributed by Serhiy Storchaka in :gh:`90953`.)

• :mod:`collections.abc`: Deprecated :class:`~collections.abc.ByteString`. Prefer :class:`!Sequence` or :class:`~collections.abc.Buffer`. For use in typing, prefer a union, like bytes | bytearray, or :class:`collections.abc.Buffer`. (Contributed by Shantanu Jain in :gh:`91896`.)

• :mod:`email`: Deprecated the isdst parameter in :func:`email.utils.localtime`. (Contributed by Alan Williams in :gh:`72346`.)

• :mod:`importlib`: __package__ and __cached__ will cease to be set or taken into consideration by the import system (:gh:`97879`).

• :mod:`importlib.abc` deprecated classes:

  • :class:`!importlib.abc.ResourceReader`
  • :class:`!importlib.abc.Traversable`
  • :class:`!importlib.abc.TraversableResources`

  Use :mod:`importlib.resources.abc` classes instead:

  • :class:`importlib.resources.abc.Traversable`
  • :class:`importlib.resources.abc.TraversableResources`

  (Contributed by Jason R. Coombs and Hugo van Kemenade in :gh:`93963`.)

• :mod:`itertools` had undocumented, inefficient, historically buggy, and inconsistent support for copy, deepcopy, and pickle operations. This will be removed in 3.14 for a significant reduction in code volume and maintenance burden. (Contributed by Raymond Hettinger in :gh:`101588`.)

• :mod:`multiprocessing`: The default start method will change to a safer one on Linux, BSDs, and other non-macOS POSIX platforms where 'fork' is currently the default (:gh:`84559`). Adding a runtime warning about this was deemed too disruptive as the majority of code is not expected to care. Use the :func:`~multiprocessing.get_context` or :func:`~multiprocessing.set_start_method` APIs to explicitly specify when your code requires 'fork'. See :ref:`multiprocessing-start-methods`.

• :mod:`pathlib`: :meth:`~pathlib.PurePath.is_relative_to`, :meth:`~pathlib.PurePath.relative_to`: passing additional arguments is deprecated.

• :func:`pkgutil.find_loader` and :func:`pkgutil.get_loader` now raise :exc:`DeprecationWarning`; use :func:`importlib.util.find_spec` instead. (Contributed by Nikita Sobolev in :gh:`97850`.)

• :mod:`pty`:

  • master_open(): use :func:`pty.openpty`.
  • slave_open(): use :func:`pty.openpty`.

• :func:`shutil.rmtree` onerror parameter is deprecated in 3.12, and will be removed in 3.14: use the onexc parameter instead.

• :mod:`sqlite3`:

  • :data:`~sqlite3.version` and :data:`~sqlite3.version_info`.
  • :meth:`~sqlite3.Cursor.execute` and :meth:`~sqlite3.Cursor.executemany` if :ref:`named placeholders <sqlite3-placeholders>` are used and parameters is a sequence instead of a :class:`dict`.
  • date and datetime adapter, date and timestamp converter: see the :mod:`sqlite3` documentation for suggested replacement recipes.

• :class:`types.CodeType`: Accessing co_lnotab was deprecated in PEP 626 since 3.10 and was planned to be removed in 3.12, but it only got a proper :exc:`DeprecationWarning` in 3.12. May be removed in 3.14. (Contributed by Nikita Sobolev in :gh:`101866`.)

• :mod:`typing`: :class:`~typing.ByteString`, deprecated since Python 3.9, now causes a :exc:`DeprecationWarning` to be emitted when it is used.

• :class:`!urllib.parse.Quoter` is deprecated: it was not intended to be a public API. (Contributed by Gregory P. Smith in :gh:`88168`.)

• :mod:`xml.etree.ElementTree`: Testing the truth value of an :class:`~xml.etree.ElementTree.Element` is deprecated and will raise an exception in Python 3.14.

Pending Removal in Python 3.15

• :class:`http.server.CGIHTTPRequestHandler` will be removed along with its related --cgi flag to python -m http.server. It was obsolete and rarely used. No direct replacement exists. Anything is better than CGI to interface a web server with a request handler.
• :class:`locale`: :func:`locale.getdefaultlocale` was deprecated in Python 3.11 and originally planned for removal in Python 3.13 (:gh:`90817`), but removal has been postponed to Python 3.15. Use :func:`locale.setlocale()`, :func:`locale.getencoding()` and :func:`locale.getlocale()` instead. (Contributed by Hugo van Kemenade in :gh:`111187`.)
• :class:`typing.NamedTuple`:
  • The undocumented keyword argument syntax for creating NamedTuple classes (NT = NamedTuple("NT", x=int)) is deprecated, and will be disallowed in 3.15. Use the class-based syntax or the functional syntax instead.
  • When using the functional syntax to create a NamedTuple class, failing to pass a value to the 'fields' parameter (NT = NamedTuple("NT")) is deprecated. Passing None to the 'fields' parameter (NT = NamedTuple("NT", None)) is also deprecated. Both will be disallowed in Python 3.15. To create a NamedTuple class with 0 fields, use class NT(NamedTuple): pass or NT = NamedTuple("NT", []).
• :class:`typing.TypedDict`: When using the functional syntax to create a TypedDict class, failing to pass a value to the 'fields' parameter (TD = TypedDict("TD")) is deprecated. Passing None to the 'fields' parameter (TD = TypedDict("TD", None)) is also deprecated. Both will be disallowed in Python 3.15. To create a TypedDict class with 0 fields, use class TD(TypedDict): pass or TD = TypedDict("TD", {}).
• :mod:`wave`: Deprecate the getmark(), setmark() and getmarkers() methods of the :class:`wave.Wave_read` and :class:`wave.Wave_write` classes. They will be removed in Python 3.15. (Contributed by Victor Stinner in :gh:`105096`.)
• Passing any arguments to :func:`threading.RLock` is now deprecated. C version allows any numbers of args and kwargs, but they are just ignored. Python version does not allow any arguments. All arguments will be removed from :func:`threading.RLock` in Python 3.15. (Contributed by Nikita Sobolev in :gh:`102029`.)

Pending Removal in Python 3.16

• :class:`array.array` 'u' type (:c:type:`wchar_t`): use the 'w' type instead (Py_UCS4).

Pending Removal in Future Versions

The following APIs were deprecated in earlier Python versions and will be removed, although there is currently no date scheduled for their removal.

• :mod:`argparse`: Nesting argument groups and nesting mutually exclusive groups are deprecated.
• :mod:`builtins`:
  • ~bool, bitwise inversion on bool.
  • bool(NotImplemented).
  • Generators: throw(type, exc, tb) and athrow(type, exc, tb) signature is deprecated: use throw(exc) and athrow(exc) instead, the single argument signature.
  • Currently Python accepts numeric literals immediately followed by keywords, for example 0in x, 1or x, 0if 1else 2. It allows confusing and ambiguous expressions like [0x1for x in y] (which can be interpreted as [0x1 for x in y] or [0x1f or x in y]). A syntax warning is raised if the numeric literal is immediately followed by one of keywords :keyword:`and`, :keyword:`else`, :keyword:`for`, :keyword:`if`, :keyword:`in`, :keyword:`is` and :keyword:`or`. In a future release it will be changed to a syntax error. (:gh:`87999`)
  • Support for __index__() and __int__() method returning non-int type: these methods will be required to return an instance of a strict subclass of :class:`int`.
  • Support for __float__() method returning a strict subclass of :class:`float`: these methods will be required to return an instance of :class:`float`.
  • Support for __complex__() method returning a strict subclass of :class:`complex`: these methods will be required to return an instance of :class:`complex`.
  • Delegation of int() to __trunc__() method.
• :mod:`calendar`: calendar.January and calendar.February constants are deprecated and replaced by :data:`calendar.JANUARY` and :data:`calendar.FEBRUARY`. (Contributed by Prince Roshan in :gh:`103636`.)
• :mod:`datetime`:
  • :meth:`~datetime.datetime.utcnow`: use datetime.datetime.now(tz=datetime.UTC).
  • :meth:`~datetime.datetime.utcfromtimestamp`: use datetime.datetime.fromtimestamp(timestamp, tz=datetime.UTC).
• :mod:`gettext`: Plural value must be an integer.
• :mod:`importlib`:
  • load_module() method: use exec_module() instead.
  • :func:`~importlib.util.cache_from_source` debug_override parameter is deprecated: use the optimization parameter instead.
• :mod:`importlib.metadata`:
  • EntryPoints tuple interface.
  • Implicit None on return values.
• :mod:`mailbox`: Use of StringIO input and text mode is deprecated, use BytesIO and binary mode instead.
• :mod:`os`: Calling :func:`os.register_at_fork` in multi-threaded process.
• :class:`!pydoc.ErrorDuringImport`: A tuple value for exc_info parameter is deprecated, use an exception instance.
• :mod:`re`: More strict rules are now applied for numerical group references and group names in regular expressions. Only sequence of ASCII digits is now accepted as a numerical reference. The group name in bytes patterns and replacement strings can now only contain ASCII letters and digits and underscore. (Contributed by Serhiy Storchaka in :gh:`91760`.)
• :mod:`ssl` options and protocols:
  • :class:`ssl.SSLContext` without protocol argument is deprecated.
  • :class:`ssl.SSLContext`: :meth:`~ssl.SSLContext.set_npn_protocols` and :meth:`!~ssl.SSLContext.selected_npn_protocol` are deprecated: use ALPN instead.
  • ssl.OP_NO_SSL* options
  • ssl.OP_NO_TLS* options
  • ssl.PROTOCOL_SSLv3
  • ssl.PROTOCOL_TLS
  • ssl.PROTOCOL_TLSv1
  • ssl.PROTOCOL_TLSv1_1
  • ssl.PROTOCOL_TLSv1_2
  • ssl.TLSVersion.SSLv3
  • ssl.TLSVersion.TLSv1
  • ssl.TLSVersion.TLSv1_1
• :mod:`!sre_compile`, :mod:`!sre_constants` and :mod:`!sre_parse` modules.
• types.CodeType.co_lnotab: use the co_lines attribute instead.
• :class:`typing.Text` (:gh:`92332`).
• :func:`sysconfig.is_python_build` check_home parameter is deprecated and ignored.
• :mod:`threading` methods:
  • :meth:`!threading.Condition.notifyAll`: use :meth:`~threading.Condition.notify_all`.
  • :meth:`!threading.Event.isSet`: use :meth:`~threading.Event.is_set`.
  • :meth:`!threading.Thread.isDaemon`, :meth:`threading.Thread.setDaemon`: use :attr:`threading.Thread.daemon` attribute.
  • :meth:`!threading.Thread.getName`, :meth:`threading.Thread.setName`: use :attr:`threading.Thread.name` attribute.
  • :meth:`!threading.currentThread`: use :meth:`threading.current_thread`.
  • :meth:`!threading.activeCount`: use :meth:`threading.active_count`.
• :class:`unittest.IsolatedAsyncioTestCase`: it is deprecated to return a value that is not None from a test case.
• :mod:`urllib.request`: :class:`~urllib.request.URLopener` and :class:`~urllib.request.FancyURLopener` style of invoking requests is deprecated. Use newer :func:`~urllib.request.urlopen` functions and methods.
• :func:`!urllib.parse.to_bytes`.
• :mod:`urllib.parse` deprecated functions: :func:`~urllib.parse.urlparse` instead
  • splitattr()
  • splithost()
  • splitnport()
  • splitpasswd()
  • splitport()
  • splitquery()
  • splittag()
  • splittype()
  • splituser()
  • splitvalue()
• :mod:`wsgiref`: SimpleHandler.stdout.write() should not do partial writes.
• :meth:`zipimport.zipimporter.load_module` is deprecated: use :meth:`~zipimport.zipimporter.exec_module` instead.

Removed

PEP 594: dead batteries

• PEP 594 removed 19 modules from the standard library, deprecated in Python 3.11:

  • :mod:`!aifc`. (Contributed by Victor Stinner in :gh:`104773`.)

  • :mod:`!audioop`. (Contributed by Victor Stinner in :gh:`104773`.)

  • :mod:`!chunk`. (Contributed by Victor Stinner in :gh:`104773`.)

  • :mod:`!cgi` and :mod:`!cgitb`.

    • cgi.FieldStorage can typically be replaced with :func:`urllib.parse.parse_qsl` for GET and HEAD requests, and the :mod:`email.message` module or multipart PyPI project for POST and PUT.

    • cgi.parse() can be replaced by calling :func:`urllib.parse.parse_qs` directly on the desired query string, except for multipart/form-data input, which can be handled as described for cgi.parse_multipart().

    • cgi.parse_header() can be replaced with the functionality in the :mod:`email` package, which implements the same MIME RFCs. For example, with :class:`email.message.EmailMessage`:

      from email.message import EmailMessage
      msg = EmailMessage()
      msg['content-type'] = 'application/json; charset="utf8"'
      main, params = msg.get_content_type(), msg['content-type'].params
      

    • cgi.parse_multipart() can be replaced with the functionality in the :mod:`email` package (e.g. :class:`email.message.EmailMessage` and :class:`email.message.Message`) which implements the same MIME RFCs, or with the multipart PyPI project.

    (Contributed by Victor Stinner in :gh:`104773`.)

  • :mod:`!crypt` module and its private :mod:`!_crypt` extension. The :mod:`hashlib` module is a potential replacement for certain use cases. Otherwise, the following PyPI projects can be used:

    • bcrypt: Modern password hashing for your software and your servers.
    • passlib: Comprehensive password hashing framework supporting over 30 schemes.
    • argon2-cffi: The secure Argon2 password hashing algorithm.
    • legacycrypt: Wrapper to the POSIX crypt library call and associated functionality.

    (Contributed by Victor Stinner in :gh:`104773`.)

  • :mod:`!imghdr`: use the projects filetype, puremagic, or python-magic instead. (Contributed by Victor Stinner in :gh:`104773`.)

  • :mod:`!mailcap`. The :mod:`mimetypes` module provides an alternative. (Contributed by Victor Stinner in :gh:`104773`.)

  • :mod:`!msilib`. (Contributed by Zachary Ware in :gh:`104773`.)

  • :mod:`!nis`. (Contributed by Victor Stinner in :gh:`104773`.)

  • :mod:`!nntplib`: the PyPI nntplib project can be used instead. (Contributed by Victor Stinner in :gh:`104773`.)

  • :mod:`!ossaudiodev`: use the pygame project for audio playback. (Contributed by Victor Stinner in :gh:`104780`.)

  • :mod:`!pipes`: use the :mod:`subprocess` module instead. (Contributed by Victor Stinner in :gh:`104773`.)

  • :mod:`!sndhdr`: use the projects filetype, puremagic, or python-magic instead. (Contributed by Victor Stinner in :gh:`104773`.)

  • :mod:`!spwd`: the python-pam project can be used instead. (Contributed by Victor Stinner in :gh:`104773`.)

  • :mod:`!sunau`. (Contributed by Victor Stinner in :gh:`104773`.)

  • :mod:`!telnetlib`, use the projects telnetlib3 or Exscript instead. (Contributed by Victor Stinner in :gh:`104773`.)

  • :mod:`!uu`: the :mod:`base64` module is a modern alternative. (Contributed by Victor Stinner in :gh:`104773`.)

  • :mod:`!xdrlib`. (Contributed by Victor Stinner in :gh:`104773`.)

2to3

• Remove the 2to3 program and the :mod:`!lib2to3` module, deprecated in Python 3.11. (Contributed by Victor Stinner in :gh:`104780`.)

configparser

• Remove the undocumented :class:`!configparser.LegacyInterpolation` class, deprecated in the docstring since Python 3.2, and with a deprecation warning since Python 3.11. (Contributed by Hugo van Kemenade in :gh:`104886`.)

importlib

• Remove :mod:`importlib.resources` deprecated methods:

  • contents()
  • is_resource()
  • open_binary()
  • open_text()
  • path()
  • read_binary()
  • read_text()

  Use :func:`importlib.resources.files()` instead. Refer to importlib-resources: Migrating from Legacy for migration advice. (Contributed by Jason R. Coombs in :gh:`106532`.)

locale

• Remove locale.resetlocale() function deprecated in Python 3.11: use locale.setlocale(locale.LC_ALL, "") instead. (Contributed by Victor Stinner in :gh:`104783`.)

logging

• :mod:`logging`: Remove undocumented and untested Logger.warn() and LoggerAdapter.warn() methods and logging.warn() function. Deprecated since Python 3.3, they were aliases to the :meth:`logging.Logger.warning` method, :meth:`!logging.LoggerAdapter.warning` method and :func:`logging.warning` function. (Contributed by Victor Stinner in :gh:`105376`.)

pathlib

• Remove support for using :class:`pathlib.Path` objects as context managers. This functionality was deprecated and made a no-op in Python 3.9.

re

• Remove undocumented, never working, and deprecated re.template function and re.TEMPLATE flag (and re.T alias). (Contributed by Serhiy Storchaka and Nikita Sobolev in :gh:`105687`.)

tkinter

• Remove the :mod:`!tkinter.tix` module, deprecated in Python 3.6. The third-party Tix library which the module wrapped is unmaintained. (Contributed by Zachary Ware in :gh:`75552`.)

turtle

• Remove the :meth:`!turtle.RawTurtle.settiltangle` method, deprecated in docs since Python 3.1 and with a deprecation warning since Python 3.11. (Contributed by Hugo van Kemenade in :gh:`104876`.)

typing

• Namespaces typing.io and typing.re, deprecated in Python 3.8, are now removed. The items in those namespaces can be imported directly from :mod:`typing`. (Contributed by Sebastian Rittau in :gh:`92871`.)
• Remove support for the keyword-argument method of creating :class:`typing.TypedDict` types, deprecated in Python 3.11. (Contributed by Tomas Roun in :gh:`104786`.)

unittest

• Removed the following :mod:`unittest` functions, deprecated in Python 3.11:

  • :func:`!unittest.findTestCases`
  • :func:`!unittest.makeSuite`
  • :func:`!unittest.getTestCaseNames`

  Use :class:`~unittest.TestLoader` methods instead:

  • :meth:`unittest.TestLoader.loadTestsFromModule`
  • :meth:`unittest.TestLoader.loadTestsFromTestCase`
  • :meth:`unittest.TestLoader.getTestCaseNames`

  (Contributed by Hugo van Kemenade in :gh:`104835`.)

• Remove the untested and undocumented :meth:`!unittest.TestProgram.usageExit` method, deprecated in Python 3.11. (Contributed by Hugo van Kemenade in :gh:`104992`.)

urllib

• Remove cafile, capath and cadefault parameters of the :func:`urllib.request.urlopen` function, deprecated in Python 3.6: use the context parameter instead. Please use :meth:`ssl.SSLContext.load_cert_chain` instead, or let :func:`ssl.create_default_context` select the system's trusted CA certificates for you. (Contributed by Victor Stinner in :gh:`105382`.)

webbrowser

• Remove the untested and undocumented :mod:`webbrowser` :class:`!MacOSX` class, deprecated in Python 3.11. Use the :class:`!MacOSXOSAScript` class (introduced in Python 3.2) instead. (Contributed by Hugo van Kemenade in :gh:`104804`.)
• Remove deprecated webbrowser.MacOSXOSAScript._name attribute. Use :attr:`webbrowser.MacOSXOSAScript.name <webbrowser.controller.name>` attribute instead. (Contributed by Nikita Sobolev in :gh:`105546`.)

Others

• None yet

CPython bytecode changes

• The oparg of YIELD_VALUE is now 1 if the yield is part of a yield-from or await, and 0 otherwise. The oparg of RESUME was changed to add a bit indicating whether the except-depth is 1, which is needed to optimize closing of generators. (Contributed by Irit Katriel in :gh:`111354`.)

Porting to Python 3.13

This section lists previously described changes and other bugfixes that may require changes to your code.

Changes in the Python API

• :meth:`!tkinter.Text.count` now always returns an integer if one or less counting options are specified. Previously it could return a single count as a 1-tuple, an integer (only if option "update" was specified) or None if no items found. The result is now the same if wantobjects is set to 0. (Contributed by Serhiy Storchaka in :gh:`97928`.)

Build Changes

• Autoconf 2.71 and aclocal 1.16.4 is now required to regenerate the :file:`configure` script. (Contributed by Christian Heimes in :gh:`89886`.)
• SQLite 3.15.2 or newer is required to build the :mod:`sqlite3` extension module. (Contributed by Erlend Aasland in :gh:`105875`.)
• Python built with :file:`configure` :option:`--with-trace-refs` (tracing references) is now ABI compatible with Python release build and :ref:`debug build <debug-build>`. (Contributed by Victor Stinner in :gh:`108634`.)
• Building CPython now requires a compiler with support for the C11 atomic library, GCC built-in atomic functions, or MSVC interlocked intrinsics.
• The errno, md5, resource, winsound, _ctypes_test, _multiprocessing.posixshmem, _scproxy, _stat, _testimportmultiple and _uuid C extensions are now built with the :ref:`limited C API <limited-c-api>`. (Contributed by Victor Stinner in :gh:`85283`.)

C API Changes

New Features

• You no longer have to define the PY_SSIZE_T_CLEAN macro before including :file:`Python.h` when using # formats in :ref:`format codes <arg-parsing-string-and-buffers>`. APIs accepting the format codes always use Py_ssize_t for # formats. (Contributed by Inada Naoki in :gh:`104922`.)

• Add :c:func:`PyImport_AddModuleRef`: similar to :c:func:`PyImport_AddModule`, but return a :term:`strong reference` instead of a :term:`borrowed reference`. (Contributed by Victor Stinner in :gh:`105922`.)

• Add :c:func:`PyWeakref_GetRef` function: similar to :c:func:`PyWeakref_GetObject` but returns a :term:`strong reference`, or NULL if the referent is no longer live. (Contributed by Victor Stinner in :gh:`105927`.)

• Add :c:func:`PyObject_GetOptionalAttr` and :c:func:`PyObject_GetOptionalAttrString`, variants of :c:func:`PyObject_GetAttr` and :c:func:`PyObject_GetAttrString` which don't raise :exc:`AttributeError` if the attribute is not found. These variants are more convenient and faster if the missing attribute should not be treated as a failure. (Contributed by Serhiy Storchaka in :gh:`106521`.)

• Add :c:func:`PyMapping_GetOptionalItem` and :c:func:`PyMapping_GetOptionalItemString`: variants of :c:func:`PyObject_GetItem` and :c:func:`PyMapping_GetItemString` which don't raise :exc:`KeyError` if the key is not found. These variants are more convenient and faster if the missing key should not be treated as a failure. (Contributed by Serhiy Storchaka in :gh:`106307`.)

• Add fixed variants of functions which silently ignore errors:

  • :c:func:`PyObject_HasAttrWithError` replaces :c:func:`PyObject_HasAttr`.
  • :c:func:`PyObject_HasAttrStringWithError` replaces :c:func:`PyObject_HasAttrString`.
  • :c:func:`PyMapping_HasKeyWithError` replaces :c:func:`PyMapping_HasKey`.
  • :c:func:`PyMapping_HasKeyStringWithError` replaces :c:func:`PyMapping_HasKeyString`.

  New functions return not only 1 for true and 0 for false, but also -1 for error.

  (Contributed by Serhiy Storchaka in :gh:`108511`.)

• If Python is built in :ref:`debug mode <debug-build>` or :option:`with assertions <--with-assertions>`, :c:func:`PyTuple_SET_ITEM` and :c:func:`PyList_SET_ITEM` now check the index argument with an assertion. If the assertion fails in :c:func:`PyTuple_SET_ITEM`, make sure that the tuple size is set before. (Contributed by Victor Stinner in :gh:`106168`.)

• Add :c:func:`PyModule_Add` function: similar to :c:func:`PyModule_AddObjectRef` and :c:func:`PyModule_AddObject` but always steals a reference to the value. (Contributed by Serhiy Storchaka in :gh:`86493`.)

• Added :c:func:`PyDict_GetItemRef` and :c:func:`PyDict_GetItemStringRef` functions: similar to :c:func:`PyDict_GetItemWithError` but returning a :term:`strong reference` instead of a :term:`borrowed reference`. Moreover, these functions return -1 on error and so checking PyErr_Occurred() is not needed. (Contributed by Victor Stinner in :gh:`106004`.)

• Added :c:func:`PyDict_ContainsString` function: same as :c:func:`PyDict_Contains`, but key is specified as a :c:expr:`const char*` UTF-8 encoded bytes string, rather than a :c:expr:`PyObject*`. (Contributed by Victor Stinner in :gh:`108314`.)

• Add :c:func:`Py_IsFinalizing` function: check if the main Python interpreter is :term:`shutting down <interpreter shutdown>`. (Contributed by Victor Stinner in :gh:`108014`.)

• Add :c:func:`PyLong_AsInt` function: similar to :c:func:`PyLong_AsLong`, but store the result in a C :c:expr:`int` instead of a C :c:expr:`long`. Previously, it was known as the private function :c:func:`!_PyLong_AsInt` (with an underscore prefix). (Contributed by Victor Stinner in :gh:`108014`.)

• Python built with :file:`configure` :option:`--with-trace-refs` (tracing references) now supports the :ref:`Limited API <limited-c-api>`. (Contributed by Victor Stinner in :gh:`108634`.)

• Add :c:func:`PyObject_VisitManagedDict` and :c:func:`PyObject_ClearManagedDict` functions which must be called by the traverse and clear functions of a type using :c:macro:`Py_TPFLAGS_MANAGED_DICT` flag. The pythoncapi-compat project can be used to get these functions on Python 3.11 and 3.12. (Contributed by Victor Stinner in :gh:`107073`.)

• Add :c:func:`PyUnicode_EqualToUTF8AndSize` and :c:func:`PyUnicode_EqualToUTF8` functions: compare Unicode object with a :c:expr:`const char*` UTF-8 encoded string and return true (1) if they are equal, or false (0) otherwise. These functions do not raise exceptions. (Contributed by Serhiy Storchaka in :gh:`110289`.)

• Add :c:func:`PyThreadState_GetUnchecked()` function: similar to :c:func:`PyThreadState_Get()`, but don't kill the process with a fatal error if it is NULL. The caller is responsible to check if the result is NULL. Previously, the function was private and known as _PyThreadState_UncheckedGet(). (Contributed by Victor Stinner in :gh:`108867`.)

• Add :c:func:`PySys_AuditTuple` function: similar to :c:func:`PySys_Audit`, but pass event arguments as a Python :class:`tuple` object. (Contributed by Victor Stinner in :gh:`85283`.)

• :c:func:`PyArg_ParseTupleAndKeywords` now supports non-ASCII keyword parameter names. (Contributed by Serhiy Storchaka in :gh:`110815`.)

• Add :c:func:`PyMem_RawMalloc`, :c:func:`PyMem_RawCalloc`, :c:func:`PyMem_RawRealloc` and :c:func:`PyMem_RawFree` to the limited C API (version 3.13). (Contributed by Victor Stinner in :gh:`85283`.)

• Add :c:func:`PySys_Audit` and :c:func:`PySys_AuditTuple` functions to the limited C API. (Contributed by Victor Stinner in :gh:`85283`.)

• Add :c:func:`PyErr_FormatUnraisable` function: similar to :c:func:`PyErr_WriteUnraisable`, but allow to customize the warning mesage. (Contributed by Serhiy Storchaka in :gh:`108082`.)

• Add :c:func:`PyUnicode_AsUTF8` function to the limited C API. (Contributed by Victor Stinner in :gh:`111089`.)

Porting to Python 3.13

• Python.h no longer includes the <ieeefp.h> standard header. It was included for the finite() function which is now provided by the <math.h> header. It should now be included explicitly if needed. Remove also the HAVE_IEEEFP_H macro. (Contributed by Victor Stinner in :gh:`108765`.)

• Python.h no longer includes the <unistd.h> standard header file. If needed, it should now be included explicitly. For example, it provides the functions: read(), write(), close(), isatty(), lseek(), getpid(), getcwd(), sysconf(), getpagesize(), alarm() and pause(). As a consequence, _POSIX_SEMAPHORES and _POSIX_THREADS macros are no longer defined by Python.h. The HAVE_UNISTD_H and HAVE_PTHREAD_H macros defined by Python.h can be used to decide if <unistd.h> and <pthread.h> header files can be included. (Contributed by Victor Stinner in :gh:`108765`.)

• Python.h no longer includes these standard header files: <time.h>, <sys/select.h> and <sys/time.h>. If needed, they should now be included explicitly. For example, <time.h> provides the clock() and gmtime() functions, <sys/select.h> provides the select() function, and <sys/time.h> provides the futimes(), gettimeofday() and setitimer() functions. (Contributed by Victor Stinner in :gh:`108765`.)

• Python.h no longer includes the <ctype.h> standard header file. If needed, it should now be included explicitly. For example, it provides isalpha() and tolower() functions which are locale dependent. Python provides locale independent functions, like :c:func:`!Py_ISALPHA` and :c:func:`!Py_TOLOWER`. (Contributed by Victor Stinner in :gh:`108765`.)

• If the :c:macro:`Py_LIMITED_API` macro is defined, :c:macro:`!Py_BUILD_CORE`, :c:macro:`!Py_BUILD_CORE_BUILTIN` and :c:macro:`!Py_BUILD_CORE_MODULE` macros are now undefined by <Python.h>. (Contributed by Victor Stinner in :gh:`85283`.)

• The old trashcan macros Py_TRASHCAN_SAFE_BEGIN and Py_TRASHCAN_SAFE_END were removed. They should be replaced by the new macros Py_TRASHCAN_BEGIN and Py_TRASHCAN_END.

  A tp_dealloc function that has the old macros, such as:

  static void
  mytype_dealloc(mytype *p)
  {
      PyObject_GC_UnTrack(p);
      Py_TRASHCAN_SAFE_BEGIN(p);
      ...
      Py_TRASHCAN_SAFE_END
  }
  

  should migrate to the new macros as follows:

  static void
  mytype_dealloc(mytype *p)
  {
      PyObject_GC_UnTrack(p);
      Py_TRASHCAN_BEGIN(p, mytype_dealloc)
      ...
      Py_TRASHCAN_END
  }
  

  Note that Py_TRASHCAN_BEGIN has a second argument which should be the deallocation function it is in.

• The :c:func:`PyUnicode_AsUTF8` function now raises an exception if the string contains embedded null characters. To accept embedded null characters and truncate on purpose at the first null byte, PyUnicode_AsUTF8AndSize(unicode, NULL) can be used instead. (Contributed by Victor Stinner in :gh:`111089`.)

• On Windows, Python.h no longer includes the <stddef.h> standard header file. If needed, it should now be included explicitly. For example, it provides offsetof() function, and size_t and ptrdiff_t types. Including <stddef.h> explicitly was already needed by all other platforms, the HAVE_STDDEF_H macro is only defined on Windows. (Contributed by Victor Stinner in :gh:`108765`.)

Deprecated

• Passing optional arguments maxsplit, count and flags in module-level functions :func:`re.split`, :func:`re.sub` and :func:`re.subn` as positional arguments is now deprecated. In future Python versions these parameters will be :ref:`keyword-only <keyword-only_parameter>`. (Contributed by Serhiy Storchaka in :gh:`56166`.)

• Deprecate the old Py_UNICODE and PY_UNICODE_TYPE types: use directly the :c:type:`wchar_t` type instead. Since Python 3.3, Py_UNICODE and PY_UNICODE_TYPE are just aliases to :c:type:`wchar_t`. (Contributed by Victor Stinner in :gh:`105156`.)

• Deprecate old Python initialization functions:

  • :c:func:`PySys_ResetWarnOptions`: clear :data:`sys.warnoptions` and :data:`!warnings.filters` instead.
  • :c:func:`Py_GetExecPrefix`: get :data:`sys.exec_prefix` instead.
  • :c:func:`Py_GetPath`: get :data:`sys.path` instead.
  • :c:func:`Py_GetPrefix`: get :data:`sys.prefix` instead.
  • :c:func:`Py_GetProgramFullPath`: get :data:`sys.executable` instead.
  • :c:func:`Py_GetProgramName`: get :data:`sys.executable` instead.
  • :c:func:`Py_GetPythonHome`: get :c:member:`PyConfig.home` or :envvar:`PYTHONHOME` environment variable instead.

  Functions scheduled for removal in Python 3.15. (Contributed by Victor Stinner in :gh:`105145`.)

• Deprecate the :c:func:`PyImport_ImportModuleNoBlock` function which is just an alias to :c:func:`PyImport_ImportModule` since Python 3.3. Scheduled for removal in Python 3.15. (Contributed by Victor Stinner in :gh:`105396`.)

• Deprecate the :c:func:`PyWeakref_GetObject` and :c:func:`PyWeakref_GET_OBJECT` functions, which return a :term:`borrowed reference`: use the new :c:func:`PyWeakref_GetRef` function instead, it returns a :term:`strong reference`. The pythoncapi-compat project can be used to get :c:func:`PyWeakref_GetRef` on Python 3.12 and older. (Contributed by Victor Stinner in :gh:`105927`.)

Removed

• Removed chained :class:`classmethod` descriptors (introduced in :issue:`19072`). This can no longer be used to wrap other descriptors such as :class:`property`. The core design of this feature was flawed and caused a number of downstream problems. To "pass-through" a :class:`classmethod`, consider using the :attr:`!__wrapped__` attribute that was added in Python 3.10. (Contributed by Raymond Hettinger in :gh:`89519`.)

• Remove many APIs (functions, macros, variables) with names prefixed by _Py or _PY (considered as private API). If your project is affected by one of these removals and you consider that the removed API should remain available, please open a new issue to request a public C API and add cc @vstinner to the issue to notify Victor Stinner. (Contributed by Victor Stinner in :gh:`106320`.)

• Remove functions deprecated in Python 3.9.

  • PyEval_CallObject(), PyEval_CallObjectWithKeywords(): use :c:func:`PyObject_CallNoArgs` or :c:func:`PyObject_Call` instead. Warning: :c:func:`PyObject_Call` positional arguments must be a :class:`tuple` and must not be NULL, keyword arguments must be a :class:`dict` or NULL, whereas removed functions checked arguments type and accepted NULL positional and keyword arguments. To replace PyEval_CallObjectWithKeywords(func, NULL, kwargs) with :c:func:`PyObject_Call`, pass an empty tuple as positional arguments using :c:func:`PyTuple_New(0) <PyTuple_New>`.
  • PyEval_CallFunction(): use :c:func:`PyObject_CallFunction` instead.
  • PyEval_CallMethod(): use :c:func:`PyObject_CallMethod` instead.
  • PyCFunction_Call(): use :c:func:`PyObject_Call` instead.

  (Contributed by Victor Stinner in :gh:`105107`.)

• Remove old buffer protocols deprecated in Python 3.0. Use :ref:`bufferobjects` instead.

  • :c:func:`!PyObject_CheckReadBuffer`: Use :c:func:`PyObject_CheckBuffer` to test if the object supports the buffer protocol. Note that :c:func:`PyObject_CheckBuffer` doesn't guarantee that :c:func:`PyObject_GetBuffer` will succeed. To test if the object is actually readable, see the next example of :c:func:`PyObject_GetBuffer`.

  • :c:func:`!PyObject_AsCharBuffer`, :c:func:`!PyObject_AsReadBuffer`: :c:func:`PyObject_GetBuffer` and :c:func:`PyBuffer_Release` instead:

    Py_buffer view;
    if (PyObject_GetBuffer(obj, &view, PyBUF_SIMPLE) < 0) {
        return NULL;
    }
    // Use `view.buf` and `view.len` to read from the buffer.
    // You may need to cast buf as `(const char*)view.buf`.
    PyBuffer_Release(&view);

  • :c:func:`!PyObject_AsWriteBuffer`: Use :c:func:`PyObject_GetBuffer` and :c:func:`PyBuffer_Release` instead:

    Py_buffer view;
    if (PyObject_GetBuffer(obj, &view, PyBUF_WRITABLE) < 0) {
        return NULL;
    }
    // Use `view.buf` and `view.len` to write to the buffer.
    PyBuffer_Release(&view);

  (Contributed by Inada Naoki in :gh:`85275`.)

• Remove the following old functions to configure the Python initialization, deprecated in Python 3.11:

  • PySys_AddWarnOptionUnicode(): use :c:member:`PyConfig.warnoptions` instead.
  • PySys_AddWarnOption(): use :c:member:`PyConfig.warnoptions` instead.
  • PySys_AddXOption(): use :c:member:`PyConfig.xoptions` instead.
  • PySys_HasWarnOptions(): use :c:member:`PyConfig.xoptions` instead.
  • PySys_SetArgvEx(): set :c:member:`PyConfig.argv` instead.
  • PySys_SetArgv(): set :c:member:`PyConfig.argv` instead.
  • PySys_SetPath(): set :c:member:`PyConfig.module_search_paths` instead.
  • Py_SetPath(): set :c:member:`PyConfig.module_search_paths` instead.
  • Py_SetProgramName(): set :c:member:`PyConfig.program_name` instead.
  • Py_SetPythonHome(): set :c:member:`PyConfig.home` instead.
  • Py_SetStandardStreamEncoding(): set :c:member:`PyConfig.stdio_encoding` instead, and set also maybe :c:member:`PyConfig.legacy_windows_stdio` (on Windows).
  • _Py_SetProgramFullPath(): set :c:member:`PyConfig.executable` instead.

  Use the new :c:type:`PyConfig` API of the :ref:`Python Initialization Configuration <init-config>` instead (PEP 587), added to Python 3.8. (Contributed by Victor Stinner in :gh:`105145`.)

• Remove the old trashcan macros Py_TRASHCAN_SAFE_BEGIN and Py_TRASHCAN_SAFE_END. They should be replaced by the new macros Py_TRASHCAN_BEGIN and Py_TRASHCAN_END. The new macros were added in Python 3.8 and the old macros were deprecated in Python 3.11. (Contributed by Irit Katriel in :gh:`105111`.)

• Remove PyEval_InitThreads() and PyEval_ThreadsInitialized() functions, deprecated in Python 3.9. Since Python 3.7, Py_Initialize() always creates the GIL: calling PyEval_InitThreads() did nothing and PyEval_ThreadsInitialized() always returned non-zero. (Contributed by Victor Stinner in :gh:`105182`.)

• Remove PyEval_AcquireLock() and PyEval_ReleaseLock() functions, deprecated in Python 3.2. They didn't update the current thread state. They can be replaced with:

  • :c:func:`PyEval_SaveThread` and :c:func:`PyEval_RestoreThread`;
  • low-level :c:func:`PyEval_AcquireThread` and :c:func:`PyEval_RestoreThread`;
  • or :c:func:`PyGILState_Ensure` and :c:func:`PyGILState_Release`.

  (Contributed by Victor Stinner in :gh:`105182`.)

• Remove the old aliases to functions calling functions which were kept for backward compatibility with Python 3.8 provisional API:

  • _PyObject_CallMethodNoArgs(): use PyObject_CallMethodNoArgs()
  • _PyObject_CallMethodOneArg(): use PyObject_CallMethodOneArg()
  • _PyObject_CallOneArg(): use PyObject_CallOneArg()
  • _PyObject_FastCallDict(): use PyObject_VectorcallDict()
  • _PyObject_Vectorcall(): use PyObject_Vectorcall()
  • _PyObject_VectorcallMethod(): use PyObject_VectorcallMethod()
  • _PyVectorcall_Function(): use PyVectorcall_Function()

  Just remove the underscore prefix to update your code. (Contributed by Victor Stinner in :gh:`106084`.)

• Remove private _PyObject_FastCall() function: use PyObject_Vectorcall() which is available since Python 3.8 (PEP 590). (Contributed by Victor Stinner in :gh:`106023`.)

• Remove cpython/pytime.h header file: it only contained private functions. (Contributed by Victor Stinner in :gh:`106316`.)

• Remove _PyInterpreterState_Get() alias to :c:func:`PyInterpreterState_Get()` which was kept for backward compatibility with Python 3.8. The pythoncapi-compat project can be used to get :c:func:`PyInterpreterState_Get()` on Python 3.8 and older. (Contributed by Victor Stinner in :gh:`106320`.)

• The :c:func:`PyModule_AddObject` function is now :term:`soft deprecated`: :c:func:`PyModule_Add` or :c:func:`PyModule_AddObjectRef` functions should be used instead. (Contributed by Serhiy Storchaka in :gh:`86493`.)

Pending Removal in Python 3.14

• Creating immutable types (:c:macro:`Py_TPFLAGS_IMMUTABLETYPE`) with mutable bases using the C API.

• Global configuration variables:

  • :c:var:`Py_DebugFlag`: use :c:member:`PyConfig.parser_debug`
  • :c:var:`Py_VerboseFlag`: use :c:member:`PyConfig.verbose`
  • :c:var:`Py_QuietFlag`: use :c:member:`PyConfig.quiet`
  • :c:var:`Py_InteractiveFlag`: use :c:member:`PyConfig.interactive`
  • :c:var:`Py_InspectFlag`: use :c:member:`PyConfig.inspect`
  • :c:var:`Py_OptimizeFlag`: use :c:member:`PyConfig.optimization_level`
  • :c:var:`Py_NoSiteFlag`: use :c:member:`PyConfig.site_import`
  • :c:var:`Py_BytesWarningFlag`: use :c:member:`PyConfig.bytes_warning`
  • :c:var:`Py_FrozenFlag`: use :c:member:`PyConfig.pathconfig_warnings`
  • :c:var:`Py_IgnoreEnvironmentFlag`: use :c:member:`PyConfig.use_environment`
  • :c:var:`Py_DontWriteBytecodeFlag`: use :c:member:`PyConfig.write_bytecode`
  • :c:var:`Py_NoUserSiteDirectory`: use :c:member:`PyConfig.user_site_directory`
  • :c:var:`Py_UnbufferedStdioFlag`: use :c:member:`PyConfig.buffered_stdio`
  • :c:var:`Py_HashRandomizationFlag`: use :c:member:`PyConfig.use_hash_seed` and :c:member:`PyConfig.hash_seed`
  • :c:var:`Py_IsolatedFlag`: use :c:member:`PyConfig.isolated`
  • :c:var:`Py_LegacyWindowsFSEncodingFlag`: use :c:member:`PyPreConfig.legacy_windows_fs_encoding`
  • :c:var:`Py_LegacyWindowsStdioFlag`: use :c:member:`PyConfig.legacy_windows_stdio`
  • :c:var:`!Py_FileSystemDefaultEncoding`: use :c:member:`PyConfig.filesystem_encoding`
  • :c:var:`!Py_HasFileSystemDefaultEncoding`: use :c:member:`PyConfig.filesystem_encoding`
  • :c:var:`!Py_FileSystemDefaultEncodeErrors`: use :c:member:`PyConfig.filesystem_errors`
  • :c:var:`!Py_UTF8Mode`: use :c:member:`PyPreConfig.utf8_mode` (see :c:func:`Py_PreInitialize`)

  The :c:func:`Py_InitializeFromConfig` API should be used with :c:type:`PyConfig` instead.

Pending Removal in Python 3.15

• :c:func:`PyImport_ImportModuleNoBlock`: use :c:func:`PyImport_ImportModule`.
• :c:func:`PyWeakref_GET_OBJECT`: use :c:func:`PyWeakref_GetRef` instead.
• :c:func:`PyWeakref_GetObject`: use :c:func:`PyWeakref_GetRef` instead.
• :c:type:`!Py_UNICODE_WIDE` type: use :c:type:`wchar_t` instead.
• :c:type:`Py_UNICODE` type: use :c:type:`wchar_t` instead.
• Python initialization functions:
  • :c:func:`PySys_ResetWarnOptions`: clear :data:`sys.warnoptions` and :data:`!warnings.filters` instead.
  • :c:func:`Py_GetExecPrefix`: get :data:`sys.exec_prefix` instead.
  • :c:func:`Py_GetPath`: get :data:`sys.path` instead.
  • :c:func:`Py_GetPrefix`: get :data:`sys.prefix` instead.
  • :c:func:`Py_GetProgramFullPath`: get :data:`sys.executable` instead.
  • :c:func:`Py_GetProgramName`: get :data:`sys.executable` instead.
  • :c:func:`Py_GetPythonHome`: get :c:member:`PyConfig.home` or :envvar:`PYTHONHOME` environment variable instead.

Pending Removal in Future Versions

The following APIs were deprecated in earlier Python versions and will be removed, although there is currently no date scheduled for their removal.

• :c:macro:`Py_TPFLAGS_HAVE_FINALIZE`: no needed since Python 3.8.
• :c:func:`PyErr_Fetch`: use :c:func:`PyErr_GetRaisedException`.
• :c:func:`PyErr_NormalizeException`: use :c:func:`PyErr_GetRaisedException`.
• :c:func:`PyErr_Restore`: use :c:func:`PyErr_SetRaisedException`.
• :c:func:`PyModule_GetFilename`: use :c:func:`PyModule_GetFilenameObject`.
• :c:func:`PyOS_AfterFork`: use :c:func:`PyOS_AfterFork_Child()`.
• :c:func:`PySlice_GetIndicesEx`.
• :c:func:`!PyUnicode_AsDecodedObject`.
• :c:func:`!PyUnicode_AsDecodedUnicode`.
• :c:func:`!PyUnicode_AsEncodedObject`.
• :c:func:`!PyUnicode_AsEncodedUnicode`.
• :c:func:`PyUnicode_READY`: not needed since Python 3.12.
• :c:func:`!_PyErr_ChainExceptions`.
• :c:member:`!PyBytesObject.ob_shash` member: call :c:func:`PyObject_Hash` instead.
• :c:member:`!PyDictObject.ma_version_tag` member.
• TLS API:
  • :c:func:`PyThread_create_key`: use :c:func:`PyThread_tss_alloc`.
  • :c:func:`PyThread_delete_key`: use :c:func:`PyThread_tss_free`.
  • :c:func:`PyThread_set_key_value`: use :c:func:`PyThread_tss_set`.
  • :c:func:`PyThread_get_key_value`: use :c:func:`PyThread_tss_get`.
  • :c:func:`PyThread_delete_key_value`: use :c:func:`PyThread_tss_delete`.
  • :c:func:`PyThread_ReInitTLS`: no longer needed.
• Remove undocumented PY_TIMEOUT_MAX constant from the limited C API. (Contributed by Victor Stinner in :gh:`110014`.)

Regression Test Changes

• Python built with :file:`configure` :option:`--with-pydebug` now supports a :option:`-X presite=package.module <-X>` command-line option. If used, it specifies a module that should be imported early in the lifecycle of the interpreter, before site.py is executed. (Contributed by Łukasz Langa in :gh:`110769`.)