Deprecations

Pending removal in Python 3.15

• The import system:

  • Setting __cached__ on a module while failing to set __spec__.cached is deprecated. In Python 3.15, __cached__ will cease to be set or take into consideration by the import system or standard library. (gh-97879)

  • Setting __package__ on a module while failing to set __spec__.parent is deprecated. In Python 3.15, __package__ will cease to be set or take into consideration by the import system or standard library. (gh-97879)

• 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.

• importlib:

  • load_module() method: use exec_module() instead.

• 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:

  • 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.

• sysconfig:

  • The check_home argument of sysconfig.is_python_build() has been deprecated since Python 3.12.

• 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.

• types:

  • 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 DeprecationWarning in 3.12. May be removed in 3.15. (Contributed by Nikita Sobolev in gh-101866.)

• typing:

  • The undocumented keyword argument syntax for creating NamedTuple classes (for example, Point = NamedTuple("Point", x=int, y=int)) has been deprecated since Python 3.13. Use the class-based syntax or the functional syntax instead.

  • When using the functional syntax of TypedDicts, failing to pass a value to the fields parameter (TD = TypedDict("TD")) or passing None (TD = TypedDict("TD", None)) has been deprecated since Python 3.13. Use class TD(TypedDict): pass or TD = TypedDict("TD", {}) to create a TypedDict with zero field.

  • 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.

• sre_compile, sre_constants and sre_parse modules.

• wave:

  • The getmark(), setmark() and getmarkers() methods of the Wave_read and Wave_write classes have been deprecated since Python 3.13.

• zipimport:

  • zipimport.zipimporter.load_module() has been deprecated since Python 3.10. Use exec_module() instead. (gh-125746.)

Pending removal in Python 3.16

• The import system:

  • Setting __loader__ on a module while failing to set __spec__.loader is deprecated. In Python 3.16, __loader__ will cease to be set or taken into consideration by the import system or the standard library.

• 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.

• asyncio:

  • asyncio.iscoroutinefunction() is deprecated and will be removed in Python 3.16; use inspect.iscoroutinefunction() instead. (Contributed by Jiahao Li and Kumar Aditya in gh-122875.)

  • asyncio policy system is deprecated and will be removed in Python 3.16. In particular, the following classes and functions are deprecated:

    • asyncio.AbstractEventLoopPolicy

    • asyncio.DefaultEventLoopPolicy

    • asyncio.WindowsSelectorEventLoopPolicy

    • asyncio.WindowsProactorEventLoopPolicy

    • asyncio.get_event_loop_policy()

    • asyncio.set_event_loop_policy()

    Users should use asyncio.run() or asyncio.Runner with loop_factory to use the desired event loop implementation.

    For example, to use asyncio.SelectorEventLoop on Windows:

    import asyncio
    
    async def main():
        ...
    
    asyncio.run(main(), loop_factory=asyncio.SelectorEventLoop)
    

    (Contributed by Kumar Aditya in gh-127949.)

• 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)).

• functools:

  • Calling the Python implementation of functools.reduce() with function or sequence as keyword arguments has been deprecated since Python 3.14.

• logging:

  Support for custom logging handlers with the strm argument is deprecated and scheduled for removal in Python 3.16. Define handlers with the stream argument instead. (Contributed by Mariusz Felisiak in gh-115032.)

• mimetypes:

  • Valid extensions start with a ‘.’ or are empty for mimetypes.MimeTypes.add_type(). Undotted extensions are deprecated and will raise a ValueError in Python 3.16. (Contributed by Hugo van Kemenade in gh-75223.)

• 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.

• sysconfig:

  • The sysconfig.expand_makefile_vars() function has been deprecated since Python 3.14. Use the vars argument of sysconfig.get_paths() instead.

• tarfile:

  • The undocumented and unused TarFile.tarfile attribute has been deprecated since Python 3.13.

Pending removal in Python 3.17

• typing:

  • Before Python 3.14, old-style unions were implemented using the private class typing._UnionGenericAlias. This class is no longer needed for the implementation, but it has been retained for backward compatibility, with removal scheduled for Python 3.17. Users should use documented introspection helpers like typing.get_origin() and typing.get_args() instead of relying on private implementation details.

Pending removal in Python 3.19

• ctypes:

  • Implicitly switching to the MSVC-compatible struct layout by setting _pack_ but not _layout_ on non-Windows platforms.

• hashlib:

  • In hash function constructors such as new() or the direct hash-named constructors such as md5() and sha256(), their optional initial data parameter could also be passed a keyword argument named data= or string= in various hashlib implementations.

    Support for the string keyword argument name is now deprecated and slated for removal in Python 3.19.

    Before Python 3.13, the string keyword parameter was not correctly supported depending on the backend implementation of hash functions. Prefer passing the initial data as a positional argument for maximum backwards compatibility.

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.

  • Passing the undocumented keyword argument prefix_chars to add_argument_group() is now deprecated.

  • The argparse.FileType type converter is deprecated.

• 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.)

• codecs: use open() instead of codecs.open(). (gh-133038)

• 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:

  • 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.)

• 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

• 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).

• The internal class typing._UnionGenericAlias is no longer used to implement typing.Union. To preserve compatibility with users using this private class, a compatibility shim will be provided until at least Python 3.17. (Contributed by Jelle Zijlstra in gh-105499.)

• 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()

• 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.

• sys._clear_type_cache() is deprecated: use sys._clear_internal_caches() instead.

C API deprecations

Pending removal in Python 3.15

• The PyImport_ImportModuleNoBlock(): Use PyImport_ImportModule() instead.

• PyWeakref_GetObject() and PyWeakref_GET_OBJECT(): Use PyWeakref_GetRef() instead. The pythoncapi-compat project can be used to get PyWeakref_GetRef() on Python 3.12 and older.

• Py_UNICODE type and the Py_UNICODE_WIDE macro: Use wchar_t instead.

• PyUnicode_AsDecodedObject(): Use PyCodec_Decode() instead.

• PyUnicode_AsDecodedUnicode(): Use PyCodec_Decode() instead; Note that some codecs (for example, “base64”) may return a type other than str, such as bytes.

• PyUnicode_AsEncodedObject(): Use PyCodec_Encode() instead.

• PyUnicode_AsEncodedUnicode(): Use PyCodec_Encode() instead; Note that some codecs (for example, “base64”) may return a type other than bytes, such as str.

• Python initialization functions, deprecated in Python 3.13:

  • Py_GetPath(): Use PyConfig_Get("module_search_paths") (sys.path) instead.

  • Py_GetPrefix(): Use PyConfig_Get("base_prefix") (sys.base_prefix) instead. Use PyConfig_Get("prefix") (sys.prefix) if virtual environments need to be handled.

  • Py_GetExecPrefix(): Use PyConfig_Get("base_exec_prefix") (sys.base_exec_prefix) instead. Use PyConfig_Get("exec_prefix") (sys.exec_prefix) if virtual environments need to be handled.

  • Py_GetProgramFullPath(): Use PyConfig_Get("executable") (sys.executable) instead.

  • Py_GetProgramName(): Use PyConfig_Get("executable") (sys.executable) instead.

  • Py_GetPythonHome(): Use PyConfig_Get("home") or the PYTHONHOME environment variable instead.

  The pythoncapi-compat project can be used to get PyConfig_Get() on Python 3.13 and older.

• Functions to configure Python’s initialization, deprecated in Python 3.11:

  • PySys_SetArgvEx(): Set PyConfig.argv instead.

  • PySys_SetArgv(): Set PyConfig.argv instead.

  • Py_SetProgramName(): Set PyConfig.program_name instead.

  • Py_SetPythonHome(): Set PyConfig.home instead.

  • PySys_ResetWarnOptions(): Clear sys.warnoptions and warnings.filters instead.

  The Py_InitializeFromConfig() API should be used with PyConfig instead.

• Global configuration variables:

  • Py_DebugFlag: Use PyConfig.parser_debug or PyConfig_Get("parser_debug") instead.

  • Py_VerboseFlag: Use PyConfig.verbose or PyConfig_Get("verbose") instead.

  • Py_QuietFlag: Use PyConfig.quiet or PyConfig_Get("quiet") instead.

  • Py_InteractiveFlag: Use PyConfig.interactive or PyConfig_Get("interactive") instead.

  • Py_InspectFlag: Use PyConfig.inspect or PyConfig_Get("inspect") instead.

  • Py_OptimizeFlag: Use PyConfig.optimization_level or PyConfig_Get("optimization_level") instead.

  • Py_NoSiteFlag: Use PyConfig.site_import or PyConfig_Get("site_import") instead.

  • Py_BytesWarningFlag: Use PyConfig.bytes_warning or PyConfig_Get("bytes_warning") instead.

  • Py_FrozenFlag: Use PyConfig.pathconfig_warnings or PyConfig_Get("pathconfig_warnings") instead.

  • Py_IgnoreEnvironmentFlag: Use PyConfig.use_environment or PyConfig_Get("use_environment") instead.

  • Py_DontWriteBytecodeFlag: Use PyConfig.write_bytecode or PyConfig_Get("write_bytecode") instead.

  • Py_NoUserSiteDirectory: Use PyConfig.user_site_directory or PyConfig_Get("user_site_directory") instead.

  • Py_UnbufferedStdioFlag: Use PyConfig.buffered_stdio or PyConfig_Get("buffered_stdio") instead.

  • Py_HashRandomizationFlag: Use PyConfig.use_hash_seed and PyConfig.hash_seed or PyConfig_Get("hash_seed") instead.

  • Py_IsolatedFlag: Use PyConfig.isolated or PyConfig_Get("isolated") instead.

  • Py_LegacyWindowsFSEncodingFlag: Use PyPreConfig.legacy_windows_fs_encoding or PyConfig_Get("legacy_windows_fs_encoding") instead.

  • Py_LegacyWindowsStdioFlag: Use PyConfig.legacy_windows_stdio or PyConfig_Get("legacy_windows_stdio") instead.

  • Py_FileSystemDefaultEncoding, Py_HasFileSystemDefaultEncoding: Use PyConfig.filesystem_encoding or PyConfig_Get("filesystem_encoding") instead.

  • Py_FileSystemDefaultEncodeErrors: Use PyConfig.filesystem_errors or PyConfig_Get("filesystem_errors") instead.

  • Py_UTF8Mode: Use PyPreConfig.utf8_mode or PyConfig_Get("utf8_mode") instead. (see Py_PreInitialize())

  The Py_InitializeFromConfig() API should be used with PyConfig to set these options. Or PyConfig_Get() can be used to get these options at runtime.

Pending removal in Python 3.18

• Deprecated private functions (gh-128863):

  • _PyBytes_Join(): use PyBytes_Join().

  • _PyDict_GetItemStringWithError(): use PyDict_GetItemStringRef().

  • _PyDict_Pop(): PyDict_Pop().

  • _PyLong_Sign(): use PyLong_GetSign().

  • _PyLong_FromDigits() and _PyLong_New(): use PyLongWriter_Create().

  • _PyThreadState_UncheckedGet(): use PyThreadState_GetUnchecked().

  • _PyUnicode_AsString(): use PyUnicode_AsUTF8().

  • _PyUnicodeWriter_Init(): replace _PyUnicodeWriter_Init(&writer) with writer = PyUnicodeWriter_Create(0).

  • _PyUnicodeWriter_Finish(): replace _PyUnicodeWriter_Finish(&writer) with PyUnicodeWriter_Finish(writer).

  • _PyUnicodeWriter_Dealloc(): replace _PyUnicodeWriter_Dealloc(&writer) with PyUnicodeWriter_Discard(writer).

  • _PyUnicodeWriter_WriteChar(): replace _PyUnicodeWriter_WriteChar(&writer, ch) with PyUnicodeWriter_WriteChar(writer, ch).

  • _PyUnicodeWriter_WriteStr(): replace _PyUnicodeWriter_WriteStr(&writer, str) with PyUnicodeWriter_WriteStr(writer, str).

  • _PyUnicodeWriter_WriteSubstring(): replace _PyUnicodeWriter_WriteSubstring(&writer, str, start, end) with PyUnicodeWriter_WriteSubstring(writer, str, start, end).

  • _PyUnicodeWriter_WriteASCIIString(): replace _PyUnicodeWriter_WriteASCIIString(&writer, str) with PyUnicodeWriter_WriteUTF8(writer, str).

  • _PyUnicodeWriter_WriteLatin1String(): replace _PyUnicodeWriter_WriteLatin1String(&writer, str) with PyUnicodeWriter_WriteUTF8(writer, str).

  • _PyUnicodeWriter_Prepare(): (no replacement).

  • _PyUnicodeWriter_PrepareKind(): (no replacement).

  • _Py_HashPointer(): use Py_HashPointer().

  • _Py_fopen_obj(): use Py_fopen().

  The pythoncapi-compat project can be used to get these new public functions on Python 3.13 and older.

Pending removal in Python 3.20

• The cval field in PyComplexObject (gh-128813). Use PyComplex_AsCComplex() and PyComplex_FromCComplex() to convert a Python complex number to/from the C Py_complex representation.

Pending removal in future versions

The following APIs are deprecated and will be removed, although there is currently no date scheduled for their removal.

• Py_TPFLAGS_HAVE_FINALIZE: Unneeded since Python 3.8.

• PyErr_Fetch(): Use PyErr_GetRaisedException() instead.

• PyErr_NormalizeException(): Use PyErr_GetRaisedException() instead.

• PyErr_Restore(): Use PyErr_SetRaisedException() instead.

• PyModule_GetFilename(): Use PyModule_GetFilenameObject() instead.

• PyOS_AfterFork(): Use PyOS_AfterFork_Child() instead.

• PySlice_GetIndicesEx(): Use PySlice_Unpack() and PySlice_AdjustIndices() instead.

• PyUnicode_READY(): Unneeded since Python 3.12

• PyErr_Display(): Use PyErr_DisplayException() instead.

• _PyErr_ChainExceptions(): Use _PyErr_ChainExceptions1() instead.

• PyBytesObject.ob_shash member: call PyObject_Hash() instead.

• Thread Local Storage (TLS) API:

  • PyThread_create_key(): Use PyThread_tss_alloc() instead.

  • PyThread_delete_key(): Use PyThread_tss_free() instead.

  • PyThread_set_key_value(): Use PyThread_tss_set() instead.

  • PyThread_get_key_value(): Use PyThread_tss_get() instead.

  • PyThread_delete_key_value(): Use PyThread_tss_delete() instead.

  • PyThread_ReInitTLS(): Unneeded since Python 3.7.