What's New In Python 3.14¶

Editor:: TBD

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

For full details, see the changelog.

Catatan

Prerelease users should be aware that this document is currently in draft form. It will be updated substantially as Python 3.14 moves towards release, so it's worth checking back even after reading earlier versions.

Summary -- Release highlights¶

New Features¶

Improved Error Messages¶

When unpacking assignment fails due to incorrect number of variables, the error message prints the received number of values in more cases than before. (Contributed by Tushar Sadhwani in gh-122239.)

>>> x, y, z = 1, 2, 3, 4
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
    x, y, z = 1, 2, 3, 4
    ^^^^^^^
ValueError: too many values to unpack (expected 3, got 4)

Other Language Changes¶

Incorrect usage of await and asynchronous comprehensions is now detected even if the code is optimized away by the -O command line option. For example, python -O -c 'assert await 1' now produces a SyntaxError. (Contributed by Jelle Zijlstra in gh-121637.)
Writes to __debug__ are now detected even if the code is optimized away by the -O command line option. For example, python -O -c 'assert (__debug__ := 1)' now produces a SyntaxError. (Contributed by Irit Katriel in gh-122245.)
Added class methods float.from_number() and complex.from_number() to convert a number to float or complex type correspondingly. They raise an error if the argument is a string. (Contributed by Serhiy Storchaka in gh-84978.)

New Modules¶

None yet.

Improved Modules¶

ast¶

Added ast.compare() for comparing two ASTs. (Contributed by Batuhan Taskaya and Jeremy Hylton in bpo-15987.)
Add support for copy.replace() for AST nodes. (Contributed by Bénédikt Tran in gh-121141.)
Docstrings are now removed from an optimized AST in optimization level 2. (Contributed by Irit Katriel in gh-123958.)

ctypes¶

The layout of bit fields in Structure and Union now matches platform defaults (GCC/Clang or MVSC) more closely. In particular, fields no longer overlap. (Contributed by Matthias Görgens in gh-97702.)
The Structure._layout_ class attribute can now be set to help match a non-default ABI. (Contributed by Petr Viktorin in gh-97702.)

dis¶

Added support for rendering full source location information of instructions, rather than only the line number. This feature is added to the following interfaces via the show_positions keyword argument:
- dis.Bytecode,
- dis.dis(), dis.distb(), and
- dis.disassemble().
This feature is also exposed via dis --show-positions.

(Contributed by Bénédikt Tran in gh-123165.)

fractions¶

Added support for converting any objects that have the as_integer_ratio() method to a Fraction. (Contributed by Serhiy Storchaka in gh-82017.)

http¶

Directory lists and error pages generated by the http.server module allow the browser to apply its default dark mode. (Contributed by Yorik Hansen in gh-123430.)

json¶

Add notes for JSON serialization errors that allow to identify the source of the error. (Contributed by Serhiy Storchaka in gh-122163.)

Enable json module to work as a script using the -m switch: python -m json. See the JSON command-line interface documentation. (Contributed by Trey Hunner in gh-122873.)

operator¶

Two new functions operator.is_none and operator.is_not_none have been added, such that operator.is_none(obj) is equivalent to obj is None and operator.is_not_none(obj) is equivalent to obj is not None. (Contributed by Raymond Hettinger and Nico Mexis in gh-115808.)

os¶

Added the os.environ.refresh() method to update os.environ with changes to the environment made by os.putenv(), by os.unsetenv(), or made outside Python in the same process. (Contributed by Victor Stinner in gh-120057.)

pathlib¶

Add methods to pathlib.Path to recursively copy or move files and directories:
- copy() copies a file or directory tree to a destination.
- copy_into() copies into a destination directory.
- move() moves a file or directory tree to a destination.
- move_into() moves into a destination directory.
(Contributed by Barney Gale in gh-73991.)

pdb¶

Hard-coded breakpoints (breakpoint() and pdb.set_trace()) now reuse the most recent Pdb instance that calls set_trace(), instead of creating a new one each time. As a result, all the instance specific data like display and commands are preserved across hard-coded breakpoints. (Contributed by Tian Gao in gh-121450.)

pickle¶

Set the default protocol version on the pickle module to 5. For more details, please see pickle protocols.
Add notes for pickle serialization errors that allow to identify the source of the error. (Contributed by Serhiy Storchaka in gh-122213.)

symtable¶

Expose the following symtable.Symbol methods:
(Contributed by Bénédikt Tran in gh-120029.)

unicodedata¶

The Unicode database has been updated to Unicode 16.0.0.

Optimizations¶

asyncio¶

asyncio now uses double linked list implementation for native tasks which speeds up execution by 10% on standard pyperformance benchmarks and reduces memory usage. (Contributed by Kumar Aditya in gh-107803.)

Deprecated¶

builtins: Passing a complex number as the real or imag argument in the complex() constructor is now deprecated; it should only be passed as a single positional argument. (Contributed by Serhiy Storchaka in gh-109218.)
os: Soft deprecate os.popen() and os.spawn* functions. They should no longer be used to write new code. The subprocess module is recommended instead. (Contributed by Victor Stinner in gh-120743.)
symtable: Deprecate symtable.Class.get_methods() due to the lack of interest. (Contributed by Bénédikt Tran in gh-119698.)

Pending Removal in Python 3.15¶

ctypes:
- The undocumented ctypes.SetPointerType() function has been deprecated since Python 3.13.
http.server:
- The obsolete and rarely used CGIHTTPRequestHandler has been deprecated since Python 3.13. No direct replacement exists. Anything is better than CGI to interface a web server with a request handler.
- The --cgi flag to the python -m http.server command-line interface has been deprecated since Python 3.13.
locale:
- The getdefaultlocale() function has been deprecated since Python 3.11. Its removal was originally planned for Python 3.13 (gh-90817), but has been postponed to Python 3.15. Use getlocale(), setlocale(), and getencoding() instead. (Contributed by Hugo van Kemenade in gh-111187.)
pathlib:
- PurePath.is_reserved() has been deprecated since Python 3.13. Use os.path.isreserved() to detect reserved paths on Windows.
platform:
- java_ver() has been deprecated since Python 3.13. This function is only useful for Jython support, has a confusing API, and is largely untested.
threading:
- RLock() will take no arguments in Python 3.15. Passing any arguments has been deprecated since Python 3.14, as the Python version does not permit any arguments, but the C version allows any number of positional or keyword arguments, ignoring every argument.
typing:
- The undocumented keyword argument syntax for creating NamedTuple classes (e.g. Point = NamedTuple("Point", x=int, y=int)) has been deprecated since Python 3.13. Use the class-based syntax or the functional syntax instead.
- The typing.no_type_check_decorator() decorator function has been deprecated since Python 3.13. After eight years in the typing module, it has yet to be supported by any major type checker.
wave:
- The getmark(), setmark(), and getmarkers() methods of the Wave_read and Wave_write classes have been deprecated since Python 3.13.

Pending Removal in Python 3.16¶

builtins:
- Bitwise inversion on boolean types, ~True or ~False has been deprecated since Python 3.12, as it produces surprising and unintuitive results (-2 and -1). Use not x instead for the logical negation of a Boolean. In the rare case that you need the bitwise inversion of the underlying integer, convert to int explicitly (~int(x)).
array:
- The 'u' format code (wchar_t) has been deprecated in documentation since Python 3.3 and at runtime since Python 3.13. Use the 'w' format code (Py_UCS4) for Unicode characters instead.
shutil:
- The ExecError exception has been deprecated since Python 3.14. It has not been used by any function in shutil since Python 3.4, and is now an alias of RuntimeError.
symtable:
- The Class.get_methods method has been deprecated since Python 3.14.
sys:
- The _enablelegacywindowsfsencoding() function has been deprecated since Python 3.13. Use the PYTHONLEGACYWINDOWSFSENCODING environment variable instead.
tarfile:
- The undocumented and unused TarFile.tarfile attribute has been deprecated since Python 3.13.

Pending Removal in Future Versions¶

The following APIs will be removed in the future, although there is currently no date scheduled for their removal.

argparse: Nesting argument groups and nesting mutually exclusive groups are deprecated.
array's 'u' format code (gh-57281)
builtins:
- 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 and, else, for, if, in, is and 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 int.
- Support for __float__() method returning a strict subclass of float: these methods will be required to return an instance of float.
- Support for __complex__() method returning a strict subclass of complex: these methods will be required to return an instance of complex.
- Delegation of int() to __trunc__() method.
- Passing a complex number as the real or imag argument in the complex() constructor is now deprecated; it should only be passed as a single positional argument. (Contributed by Serhiy Storchaka in gh-109218.)
calendar: calendar.January and calendar.February constants are deprecated and replaced by calendar.JANUARY and calendar.FEBRUARY. (Contributed by Prince Roshan in gh-103636.)
codeobject.co_lnotab: use the codeobject.co_lines() method instead.
datetime:
- utcnow(): use datetime.datetime.now(tz=datetime.UTC).
- utcfromtimestamp(): use datetime.datetime.fromtimestamp(timestamp, tz=datetime.UTC).
gettext: Plural value must be an integer.
importlib:
- load_module() method: use exec_module() instead.
- cache_from_source() debug_override parameter is deprecated: use the optimization parameter instead.
importlib.metadata:
- EntryPoints tuple interface.
- Implicit None on return values.
logging: the warn() method has been deprecated since Python 3.3, use warning() instead.
mailbox: Use of StringIO input and text mode is deprecated, use BytesIO and binary mode instead.
os: Calling os.register_at_fork() in multi-threaded process.
pydoc.ErrorDuringImport: A tuple value for exc_info parameter is deprecated, use an exception instance.
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.)
sre_compile, sre_constants and sre_parse modules.
shutil: rmtree()'s onerror parameter is deprecated in Python 3.12; use the onexc parameter instead.
ssl options and protocols:
- ssl.SSLContext without protocol argument is deprecated.
- ssl.SSLContext: set_npn_protocols() and 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
sysconfig.is_python_build() check_home parameter is deprecated and ignored.
threading methods:
- threading.Condition.notifyAll(): use notify_all().
- threading.Event.isSet(): use is_set().
- threading.Thread.isDaemon(), threading.Thread.setDaemon(): use threading.Thread.daemon attribute.
- threading.Thread.getName(), threading.Thread.setName(): use threading.Thread.name attribute.
- threading.currentThread(): use threading.current_thread().
- threading.activeCount(): use threading.active_count().
typing.Text (gh-92332).
unittest.IsolatedAsyncioTestCase: it is deprecated to return a value that is not None from a test case.
urllib.parse deprecated functions: urlparse() instead
- splitattr()
- splithost()
- splitnport()
- splitpasswd()
- splitport()
- splitquery()
- splittag()
- splittype()
- splituser()
- splitvalue()
- to_bytes()
urllib.request: URLopener and FancyURLopener style of invoking requests is deprecated. Use newer urlopen() functions and methods.
wsgiref: SimpleHandler.stdout.write() should not do partial writes.
xml.etree.ElementTree: Testing the truth value of an Element is deprecated. In a future release it will always return True. Prefer explicit len(elem) or elem is not None tests instead.
zipimport.zipimporter.load_module() is deprecated: use exec_module() instead.

Removed¶

argparse¶

Remove the type, choices, and metavar parameters of argparse.BooleanOptionalAction. They were deprecated since 3.12.

ast¶

Remove the following classes. They were all deprecated since Python 3.8, and have emitted deprecation warnings since Python 3.12:
- ast.Num
- ast.Str
- ast.Bytes
- ast.NameConstant
- ast.Ellipsis
Use 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 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 ast.Constant, which were present for compatibility with the now-removed AST classes:
- ast.Constant.n
- ast.Constant.s
Use ast.Constant.value instead.

(Contributed by Alex Waygood in gh-119562.)

asyncio¶

Remove the following classes and functions. They were all deprecated and emitted deprecation warnings since Python 3.12:
- asyncio.AbstractChildWatcher
- asyncio.SafeChildWatcher
- asyncio.MultiLoopChildWatcher
- asyncio.FastChildWatcher
- asyncio.ThreadedChildWatcher
- asyncio.PidfdChildWatcher
- asyncio.AbstractEventLoopPolicy.get_child_watcher()
- asyncio.AbstractEventLoopPolicy.set_child_watcher()
- asyncio.get_child_watcher()
- asyncio.set_child_watcher()
(Contributed by Kumar Aditya in gh-120804.)

collections.abc¶

Remove collections.abc.ByteString. It had previously raised a DeprecationWarning since Python 3.12.

email¶

Remove the isdst parameter from email.utils.localtime(). (Contributed by Hugo van Kemenade in gh-118798.)

importlib¶

Remove deprecated importlib.abc classes:
- importlib.abc.ResourceReader
- importlib.abc.Traversable
- importlib.abc.TraversableResources
Use importlib.resources.abc classes instead:
- importlib.resources.abc.Traversable
- importlib.resources.abc.TraversableResources
(Contributed by Jason R. Coombs and Hugo van Kemenade in gh-93963.)

itertools¶

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

pathlib¶

Remove support for passing additional keyword arguments to pathlib.Path. In previous versions, any such arguments are ignored.
Remove support for passing additional positional arguments to pathlib.PurePath.relative_to() and is_relative_to(). In previous versions, any such arguments are joined onto other.

pty¶

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

sqlite3¶

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

typing¶

Remove typing.ByteString. It had previously raised a DeprecationWarning since Python 3.12.

urllib¶

Remove deprecated Quoter class from urllib.parse. It had previously raised a DeprecationWarning since Python 3.11. (Contributed by Nikita Sobolev in gh-118827.)

Others¶

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

Porting to Python 3.14¶

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

Changes in the Python API¶

functools.partial is now a method descriptor. Wrap it in staticmethod() if you want to preserve the old behavior. (Contributed by Serhiy Storchaka and Dominykas Grigonis in gh-121027.)

Build Changes¶

C API Changes¶