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

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

• 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`).

• None yet.

• :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`).

• 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`.)

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

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`.)

• 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.

• 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 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`.)

• 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`.)

• 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`.)

• 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`.)

• Add show_group paramter 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`.)

• 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`.)

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

• :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:`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`.)

• :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.

• :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`.)

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

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:`importlib.resources`: First parameter to files is renamed to 'anchor'.

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

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

  Use files() instead. Refer to importlib-resources: Migrating from Legacy for migration advice.

• :func:`locale.getdefaultlocale`: use :func:`locale.setlocale()`, :func:`locale.getencoding()` and :func:`locale.getlocale()` instead (:gh:`90817`)

• :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.

• PEP 594: Remove the :mod:`!telnetlib` module, deprecated in Python 3.11: use the projects telnetlib3 or Exscript instead. (Contributed by Victor Stinner in :gh:`104773`.)

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

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

• 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`.)

• 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`.)

• 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`.)

• PEP 594: Remove the :mod:`!cgi` and :mod:`!cgitb` modules, deprecated in Python 3.11.

  • 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_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.

  • 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
    

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

• PEP 594: Remove the :mod:`!sndhdr` module, deprecated in Python 3.11: use the projects filetype, puremagic, or python-magic instead. (Contributed by Victor Stinner in :gh:`104773`.)

• PEP 594: Remove the :mod:`!pipes` module, deprecated in Python 3.11: use the :mod:`subprocess` module instead. (Contributed by Victor Stinner in :gh:`104773`.)

• PEP 594: Remove the :mod:`!ossaudiodev` module, deprecated in Python 3.11: use the pygame project for audio playback. (Contributed by Victor Stinner in :gh:`104780`.)

• PEP 594: Remove the :mod:`!sunau` module, deprecated in Python 3.11. (Contributed by Victor Stinner in :gh:`104773`.)

• PEP 594: Remove the :mod:`!mailcap` module, deprecated in Python 3.11. The :mod:`mimetypes` module provides an alternative. (Contributed by Victor Stinner in :gh:`104773`.)

• PEP 594: Remove the :mod:`!spwd` module, deprecated in Python 3.11: the python-pam project can be used instead. (Contributed by Victor Stinner in :gh:`104773`.)

• PEP 594: Remove the :mod:`!nntplib` module, deprecated in Python 3.11: the PyPI nntplib project can be used instead. (Contributed by Victor Stinner in :gh:`104773`.)

• PEP 594: Remove the :mod:`!nis` module, deprecated in Python 3.11. (Contributed by Victor Stinner in :gh:`104773`.)

• PEP 594: Remove the :mod:`!xdrlib` module, deprecated in Python 3.11. (Contributed by Victor Stinner in :gh:`104773`.)

• PEP 594: Remove the :mod:`!msilib` module, deprecated in Python 3.11. (Contributed by Zachary Ware in :gh:`104773`.)

• PEP 594: Remove the :mod:`!crypt` module and its private :mod:`!_crypt` extension, deprecated in Python 3.11. 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`.)

• PEP 594: Remove the :mod:`!uu` module, deprecated in Python 3.11: the :mod:`base64` module is a modern alternative. (Contributed by Victor Stinner in :gh:`104773`.)

• PEP 594: Remove the :mod:`!aifc` module, deprecated in Python 3.11. (Contributed by Victor Stinner in :gh:`104773`.)

• PEP 594: Remove the :mod:`!audioop` module, deprecated in Python 3.11. (Contributed by Victor Stinner in :gh:`104773`.)

• PEP 594: Remove the :mod:`!chunk` module, deprecated in Python 3.11. (Contributed by Victor Stinner in :gh:`104773`.)

• 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`.)

• PEP 594: Remove the :mod:`!imghdr` module, deprecated in Python 3.11: use the projects filetype, puremagic, or python-magic instead. (Contributed by Victor Stinner in :gh:`104773`.)

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

• 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`.)

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

• :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`.)

• 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`.)

• Remove deprecated webbrowser.MacOSXOSAScript._name attribute. Use :attr:`webbrowser.MacOSXOSAScript.name <webbrowser.controller.name>` attribute instead. (Contributed by Nikita Sobolev in :gh:`105546`.)

• 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`.)

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

• 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.

• Autoconf 2.71 and aclocal 1.16.4 is now required to regenerate :file:`!configure`. (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`.)

• 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`.)
• 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, make sure that the 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`.)

• 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`.)

• 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 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`.)

• 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.

• :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.

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.