This article explains the new features in Python 3.12, compared to 3.11.

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

Important deprecations, removals or restrictions:

• PEP 623, Remove wstr from Unicode

• None yet.

• Add :data:`os.PIDFD_NONBLOCK` to open a file descriptor for a process with :func:`os.pidfd_open` in non-blocking mode. (Contributed by Kumar Aditya in :gh:`93312`.)

• Removed wstr and wstr_length members from Unicode objects. It reduces object size by 8 or 16 bytes on 64bit platform. (PEP 623) (Contributed by Inada Naoki in :gh:`92536`.)

• Removed the :opcode:`LOAD_METHOD` instruction. It has been merged into :opcode:`LOAD_ATTR`. :opcode:`LOAD_ATTR` will now behave like the old :opcode:`LOAD_METHOD` instruction if the low bit of its oparg is set. (Contributed by Ken Jin in :gh:`93429`.)

The following modules and APIs have been deprecated in earlier Python releases, and will be removed in Python 3.13.

Modules (see PEP 594):

• :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`
• :mod:`xdrlib`

APIs:

• :class:`configparser.LegacyInterpolation` (:gh:`90765`)
• :func:`locale.getdefaultlocale` (:gh:`90817`)
• :meth:`turtle.RawTurtle.settiltangle` (:gh:`50096`)
• :func:`unittest.findTestCases` (:gh:`50096`)
• :func:`unittest.makeSuite` (:gh:`50096`)
• :func:`unittest.getTestCaseNames` (:gh:`50096`)
• :class:`webbrowser.MacOSX` (:gh:`86421`)

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

• :class:`typing.Text` (:gh:`92332`)
• 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`)

• The following undocumented :mod:`sqlite3` features, deprecated in Python 3.10, are now removed:

  • sqlite3.enable_shared_cache()
  • sqlite3.OptimizedUnicode

  If a shared cache must be used, open the database in URI mode using the cache=shared query parameter.

  The sqlite3.OptimizedUnicode text factory has been an alias for :class:`str` since Python 3.3. Code that previously set the text factory to OptimizedUnicode can either use str explicitly, or rely on the default value which is also str.

  (Contributed by Erlend E. Aasland in :gh:`92548`)

• The --experimental-isolated-subinterpreters configure flag (and corresponding EXPERIMENTAL_ISOLATED_SUBINTERPRETERS) have been removed.

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

• 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`.)
• Removed randrange() functionality deprecated since Python 3.10. Formerly, randrange(10.0) losslessly converted to randrange(10). Now, it raises a TypeError. Also, the exception raised for non-integral values such as randrange(10.5) or randrange('10') has been changed from ValueError to TypeError. This also prevents bugs where randrange(1e25) would silently select from a larger range than randrange(10**25). (Originally suggested by Serhiy Storchaka gh-86388.)

• va_start() with two parameters, like va_start(args, format), is now required to build Python. va_start() is no longer called with a single parameter. (Contributed by Kumar Aditya in :gh:`93207`.)

• Added the new limited C API function :c:func:`PyType_FromMetaclass`, which generalizes the existing :c:func:`PyType_FromModuleAndSpec` using an additional metaclass argument. (Contributed by Wenzel Jakob in :gh:`93012`.)

• Legacy Unicode APIs based on Py_UNICODE* representation has been removed. Please migrate to APIs based on UTF-8 or wchar_t*.
• Argument parsing functions like :c:func:`PyArg_ParseTuple` doesn't support Py_UNICODE* based format (e.g. u, Z) anymore. Please migrate to other formats for Unicode like s, z, es, and U.

• Remove the token.h header file. There was never any public tokenizer C API. The token.h header file was only designed to be used by Python internals. (Contributed by Victor Stinner in :gh:`92651`.)

• Leagcy Unicode APIs has been removed. See PEP 623 for detail.

  • :c:macro:`PyUnicode_WCHAR_KIND`
  • :c:func:`PyUnicode_AS_UNICODE`
  • :c:func:`PyUnicode_AsUnicode`
  • :c:func:`PyUnicode_AsUnicodeAndSize`
  • :c:func:`PyUnicode_AS_DATA`
  • :c:func:`PyUnicode_FromUnicode`
  • :c:func:`PyUnicode_GET_SIZE`
  • :c:func:`PyUnicode_GetSize`
  • :c:func:`PyUnicode_GET_DATA_SIZE`

• Remove the PyUnicode_InternImmortal() function and the SSTATE_INTERNED_IMMORTAL macro. (Contributed by Victor Stinner in :gh:`85858`.)