This article explains the new features in Python 3.14, compared to 3.13.

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

• None yet.

Added :func:`ast.compare` for comparing two ASTs. (Contributed by Batuhan Taskaya and Jeremy Hylton in :issue:`15987`.)

• Added the :data:`os.environ.refresh() <os.environ>` method to update :data:`os.environ` with changes to the environment made by :func:`os.putenv`, by :func:`os.unsetenv`, or made outside Python in the same process. (Contributed by Victor Stinner in :gh:`120057`.)

• Add :meth:`pathlib.Path.copy`, which copies the content of one file to another, like :func:`shutil.copyfile`. (Contributed by Barney Gale in :gh:`73991`.)
• Add :meth:`pathlib.Path.copytree`, which copies one directory tree to another. (Contributed by Barney Gale in :gh:`73991`.)

• Expose the following :class:`symtable.Symbol` methods:

  • :meth:`~symtable.Symbol.is_free_class`
  • :meth:`~symtable.Symbol.is_comp_iter`
  • :meth:`~symtable.Symbol.is_comp_cell`

  (Contributed by Bénédikt Tran in :gh:`120029`.)

• Passing a complex number as the real or imag argument in the :func:`complex` constructor is now deprecated; it should only be passed as a single positional argument. (Contributed by Serhiy Storchaka in :gh:`109218`.)

• Remove the type, choices, and metavar parameters of :class:`!argparse.BooleanOptionalAction`. They were deprecated since 3.12.

• Remove the following classes. They were all deprecated since Python 3.8, and have emitted deprecation warnings since Python 3.12:

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

  Use :class:`ast.Constant` instead. As a consequence of these removals, user-defined visit_Num, visit_Str, visit_Bytes, visit_NameConstant and visit_Ellipsis methods on custom :class:`ast.NodeVisitor` subclasses will no longer be called when the NodeVisitor subclass is visiting an AST. Define a visit_Constant method instead.

  Also, remove the following deprecated properties on :class:`ast.Constant`, which were present for compatibility with the now-removed AST classes:

  • :attr:`!ast.Constant.n`
  • :attr:`!ast.Constant.s`

  Use :attr:`!ast.Constant.value` instead.

  (Contributed by Alex Waygood in :gh:`119562`.)

• Remove the following classes and functions. They were all deprecated and emitted deprecation warnings since Python 3.12:

  • :class:`!asyncio.AbstractChildWatcher`
  • :class:`!asyncio.SafeChildWatcher`
  • :class:`!asyncio.MultiLoopChildWatcher`
  • :class:`!asyncio.FastChildWatcher`
  • :class:`!asyncio.ThreadedChildWatcher`
  • :class:`!asyncio.PidfdChildWatcher`
  • :meth:`!asyncio.AbstractEventLoopPolicy.get_child_watcher`
  • :meth:`!asyncio.AbstractEventLoopPolicy.set_child_watcher`
  • :func:`!asyncio.get_child_watcher`
  • :func:`!asyncio.set_child_watcher`

  (Contributed by Kumar Aditya in :gh:`120804`.)

• Remove :class:`!collections.abc.ByteString`. It had previously raised a :exc:`DeprecationWarning` since Python 3.12.

• Remove the isdst parameter from :func:`email.utils.localtime`. (Contributed by Hugo van Kemenade in :gh:`118798`.)

• Remove deprecated :mod:`importlib.abc` 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`.)

• Remove :mod:`itertools` support for copy, deepcopy, and pickle operations. These had previously raised a :exc:`DeprecationWarning` since Python 3.12. (Contributed by Raymond Hettinger in :gh:`101588`.)

• Remove support for passing additional keyword arguments to :class:`pathlib.Path`. In previous versions, any such arguments are ignored.
• Remove support for passing additional positional arguments to :meth:`pathlib.PurePath.relative_to` and :meth:`~pathlib.PurePath.is_relative_to`. In previous versions, any such arguments are joined onto other.

• Remove deprecated :func:`!pty.master_open` and :func:`!pty.slave_open`. They had previously raised a :exc:`DeprecationWarning` since Python 3.12. Use :func:`pty.openpty` instead. (Contributed by Nikita Sobolev in :gh:`118824`.)

• Remove :data:`!version` and :data:`!version_info` from :mod:`sqlite3`. (Contributed by Hugo van Kemenade in :gh:`118924`.)
• Disallow using a sequence of parameters with named placeholders. This had previously raised a :exc:`DeprecationWarning` since Python 3.12; it will now raise a :exc:`sqlite3.ProgrammingError`. (Contributed by Erlend E. Aasland in :gh:`118928` and :gh:`101693`.)

• Remove :class:`!typing.ByteString`. It had previously raised a :exc:`DeprecationWarning` since Python 3.12.

• Remove deprecated :class:`!Quoter` class from :mod:`urllib.parse`. It had previously raised a :exc:`DeprecationWarning` since Python 3.11. (Contributed by Nikita Sobolev in :gh:`118827`.)

• Using :data:`NotImplemented` in a boolean context will now raise a :exc:`TypeError`. It had previously raised a :exc:`DeprecationWarning` since Python 3.9. (Contributed by Jelle Zijlstra in :gh:`118767`.)
• The :func:`int` built-in no longer delegates to :meth:`~object.__trunc__`. Classes that want to support conversion to integer must implement either :meth:`~object.__int__` or :meth:`~object.__index__`. (Contributed by Mark Dickinson in :gh:`119743`.)

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

• Add :c:func:`PyLong_GetSign` function to get the sign of :class:`int` objects. (Contributed by Sergey B Kirpichev in :gh:`116560`.)

• Add a new :c:type:`PyUnicodeWriter` API to create a Python :class:`str` object:

  • :c:func:`PyUnicodeWriter_Create`.
  • :c:func:`PyUnicodeWriter_Discard`.
  • :c:func:`PyUnicodeWriter_Finish`.
  • :c:func:`PyUnicodeWriter_WriteChar`.
  • :c:func:`PyUnicodeWriter_WriteUTF8`.
  • :c:func:`PyUnicodeWriter_WriteUCS4`.
  • :c:func:`PyUnicodeWriter_WriteWideChar`.
  • :c:func:`PyUnicodeWriter_WriteStr`.
  • :c:func:`PyUnicodeWriter_WriteRepr`.
  • :c:func:`PyUnicodeWriter_WriteSubstring`.
  • :c:func:`PyUnicodeWriter_Format`.
  • :c:func:`PyUnicodeWriter_DecodeUTF8Stateful`.

  (Contributed by Victor Stinner in :gh:`119182`.)

• In the limited C API 3.14 and newer, :c:func:`Py_TYPE` is now implemented as an opaque function call to hide implementation details. (Contributed by Victor Stinner in :gh:`120600`.)

• Macros :c:macro:`!Py_IS_NAN`, :c:macro:`!Py_IS_INFINITY` and :c:macro:`!Py_IS_FINITE` are :term:`soft deprecated`, use instead :c:macro:`!isnan`, :c:macro:`!isinf` and :c:macro:`!isfinite` available from :file:`math.h` since C99. (Contributed by Sergey B Kirpichev in :gh:`119613`.)

• Creating :c:data:`immutable types <Py_TPFLAGS_IMMUTABLETYPE>` with mutable bases was deprecated since 3.12 and now raises a :exc:`TypeError`.