Changelog

Python 3.13.6 final

Release date: 2025-08-06

macOS

  • gh-137450: macOS installer shell path management improvements: separate the installer Shell profile updater postinstall script from the Update Shell Profile.command to enable more robust error handling.

  • gh-137134: Update macOS installer to ship with SQLite version 3.50.4.

Windows

  • gh-137134: Update Windows installer to ship with SQLite 3.50.4.

Tools/Demos

  • gh-135968: Stubs for strip are now provided as part of an iOS install.

Tests

  • gh-135966: The iOS testbed now handles the app_packages folder as a site directory.

  • gh-135494: Fix regrtest to support excluding tests from --pgo tests. Patch by Victor Stinner.

  • gh-135489: Show verbose output for failing tests during PGO profiling step with –enable-optimizations.

Security

  • gh-135661: Fix parsing start and end tags in html.parser.HTMLParser according to the HTML5 standard.

    • Whitespaces no longer accepted between </ and the tag name. E.g. </ script> does not end the script section.

    • Vertical tabulation (\v) and non-ASCII whitespaces no longer recognized as whitespaces. The only whitespaces are \t\n\r\f and space.

    • Null character (U+0000) no longer ends the tag name.

    • Attributes and slashes after the tag name in end tags are now ignored, instead of terminating after the first > in quoted attribute value. E.g. </script/foo=">"/>.

    • Multiple slashes and whitespaces between the last attribute and closing > are now ignored in both start and end tags. E.g. <a foo=bar/ //>.

    • Multiple = between attribute name and value are no longer collapsed. E.g. <a foo==bar> produces attribute “foo” with value “=bar”.

  • gh-102555: Fix comment parsing in html.parser.HTMLParser according to the HTML5 standard. --!> now ends the comment. -- > no longer ends the comment. Support abnormally ended empty comments <--> and <--->.

  • gh-135462: Fix quadratic complexity in processing specially crafted input in html.parser.HTMLParser. End-of-file errors are now handled according to the HTML5 specs – comments and declarations are automatically closed, tags are ignored.

  • gh-118350: Fix support of escapable raw text mode (elements “textarea” and “title”) in html.parser.HTMLParser.

Library

  • gh-132710: If possible, ensure that uuid.getnode() returns the same result even across different processes. Previously, the result was constant only within the same process. Patch by Bénédikt Tran.

  • gh-137273: Fix debug assertion failure in locale.setlocale() on Windows.

  • gh-137257: Bump the version of pip bundled in ensurepip to version 25.2

  • gh-81325: tarfile.TarFile now accepts a path-like when working on a tar archive. (Contributed by Alexander Enrique Urieles Nieto in gh-81325.)

  • gh-130522: Fix unraisable TypeError raised during interpreter shutdown in the threading module.

  • gh-130577: tarfile now validates archives to ensure member offsets are non-negative. (Contributed by Alexander Enrique Urieles Nieto in gh-130577.)

  • gh-136549: Fix signature of threading.excepthook().

  • gh-136523: Fix wave.Wave_write emitting an unraisable when open raises.

  • gh-52876: Add missing keepends (default True) parameter to codecs.StreamReaderWriter.readline() and codecs.StreamReaderWriter.readlines().

  • gh-85702: If zoneinfo._common.load_tzdata is given a package without a resource a zoneinfo.ZoneInfoNotFoundError is raised rather than a PermissionError. Patch by Victor Stinner.

  • gh-134759: Fix UnboundLocalError in email.message.Message.get_payload() when the payload to decode is a bytes object. Patch by Kliment Lamonov.

  • gh-136028: Fix parsing month names containing “İ” (U+0130, LATIN CAPITAL LETTER I WITH DOT ABOVE) in time.strptime(). This affects locales az_AZ, ber_DZ, ber_MA and crh_UA.

  • gh-135995: In the palmos encoding, make byte 0x9b decode to › (U+203A - SINGLE RIGHT-POINTING ANGLE QUOTATION MARK).

  • gh-53203: Fix time.strptime() for %c and %x formats on locales byn_ER, wal_ET and lzh_TW, and for %X format on locales ar_SA, bg_BG and lzh_TW.

  • gh-91555: An earlier change, which was introduced in 3.13.4, has been reverted. It disabled logging for a logger during handling of log messages for that logger. Since the reversion, the behaviour should be as it was before 3.13.4.

  • gh-135878: Fixes a crash of types.SimpleNamespace on free threading builds, when several threads were calling its __repr__() method at the same time.

  • gh-135836: Fix IndexError in asyncio.loop.create_connection() that could occur when non-OSError exception is raised during connection and socket’s close() raises OSError.

  • gh-135836: Fix IndexError in asyncio.loop.create_connection() that could occur when the Happy Eyeballs algorithm resulted in an empty exceptions list during connection attempts.

  • gh-135855: Raise TypeError instead of SystemError when _interpreters.set___main___attrs() is passed a non-dict object. Patch by Brian Schubert.

  • gh-135815: netrc: skip security checks if os.getuid() is missing. Patch by Bénédikt Tran.

  • gh-135640: Address bug where it was possible to call xml.etree.ElementTree.ElementTree.write() on an ElementTree object with an invalid root element. This behavior blanked the file passed to write if it already existed.

  • gh-135444: Fix asyncio.DatagramTransport.sendto() to account for datagram header size when data cannot be sent.

  • gh-135497: Fix os.getlogin() failing for longer usernames on BSD-based platforms.

  • gh-135487: Fix reprlib.Repr.repr_int() when given integers with more than sys.get_int_max_str_digits() digits. Patch by Bénédikt Tran.

  • gh-135335: multiprocessing: Flush stdout and stderr after preloading modules in the forkserver.

  • gh-135244: uuid: when the MAC address cannot be determined, the 48-bit node ID is now generated with a cryptographically-secure pseudo-random number generator (CSPRNG) as per RFC 9562, §6.10.3. This affects uuid1().

  • gh-135069: Fix the “Invalid error handling” exception in encodings.idna.IncrementalDecoder to correctly replace the ‘errors’ parameter.

  • gh-134698: Fix a crash when calling methods of ssl.SSLContext or ssl.SSLSocket across multiple threads.

  • gh-132124: On POSIX-compliant systems, multiprocessing.util.get_temp_dir() now ignores TMPDIR (and similar environment variables) if the path length of AF_UNIX socket files exceeds the platform-specific maximum length when using the forkserver start method. Patch by Bénédikt Tran.

  • gh-133439: Fix dot commands with trailing spaces are mistaken for multi-line SQL statements in the sqlite3 command-line interface.

  • gh-132969: Prevent the ProcessPoolExecutor executor thread, which remains running when shutdown(wait=False), from attempting to adjust the pool’s worker processes after the object state has already been reset during shutdown. A combination of conditions, including a worker process having terminated abormally, resulted in an exception and a potential hang when the still-running executor thread attempted to replace dead workers within the pool.

  • gh-130664: Support the '_' digit separator in formatting of the integral part of Decimal’s. Patch by Sergey B Kirpichev.

  • gh-85702: If zoneinfo._common.load_tzdata is given a package without a resource a ZoneInfoNotFoundError is raised rather than a IsADirectoryError.

  • gh-130664: Handle corner-case for Fraction’s formatting: treat zero-padding (preceding the width field by a zero ('0') character) as an equivalent to a fill character of '0' with an alignment type of '=', just as in case of float’s.

Documentation

  • gh-135171: Document that the iterator for the leftmost for clause in the generator expression is created immediately.

Core and Builtins

  • gh-58124: Fix name of the Python encoding in Unicode errors of the code page codec: use “cp65000” and “cp65001” instead of “CP_UTF7” and “CP_UTF8” which are not valid Python code names. Patch by Victor Stinner.

  • gh-137314: Fixed a regression where raw f-strings incorrectly interpreted escape sequences in format specifications. Raw f-strings now properly preserve literal backslashes in format specs, matching the behavior from Python 3.11. For example, rf"{obj:\xFF}" now correctly produces '\\xFF' instead of 'ÿ'. Patch by Pablo Galindo.

  • gh-136541: Fix some issues with the perf trampolines on x86-64 and aarch64. The trampolines were not being generated correctly for some cases, which could lead to the perf integration not working correctly. Patch by Pablo Galindo.

  • gh-109700: Fix memory error handling in PyDict_SetDefault().

  • gh-78465: Fix error message for cls.__new__(cls, ...) where cls is not instantiable builtin or extension type (with tp_new set to NULL).

  • gh-135871: Non-blocking mutex lock attempts now return immediately when the lock is busy instead of briefly spinning in the free threading build.

  • gh-135607: Fix potential weakref races in an object’s destructor on the free threaded build.

  • gh-135496: Fix typo in the f-string conversion type error (“exclamanation” -> “exclamation”).

  • gh-130077: Properly raise custom syntax errors when incorrect syntax containing names that are prefixes of soft keywords is encountered. Patch by Pablo Galindo.

  • gh-135148: Fixed a bug where f-string debug expressions (using =) would incorrectly strip out parts of strings containing escaped quotes and # characters. Patch by Pablo Galindo.

  • gh-133136: Limit excess memory usage in the free threading build when a large dictionary or list is resized and accessed by multiple threads.

  • gh-132617: Fix dict.update() modification check that could incorrectly raise a “dict mutated during update” error when a different dictionary was modified that happens to share the same underlying keys object.

  • gh-91153: Fix a crash when a bytearray is concurrently mutated during item assignment.

  • gh-127971: Fix off-by-one read beyond the end of a string in string search.

  • gh-125723: Fix crash with gi_frame.f_locals when generator frames outlive their generator. Patch by Mikhail Efimov.

Build

  • gh-135497: Fix the detection of MAXLOGNAME in the configure.ac script.

Python 3.13.5 final

Release date: 2025-06-11

Windows

  • gh-135151: Avoid distributing modified pyconfig.h in the traditional installer. Extension module builds must always specify Py_GIL_DISABLED when targeting the free-threaded runtime.

Tests

Library

  • gh-133967: Do not normalize locale name ‘C.UTF-8’ to ‘en_US.UTF-8’.

  • gh-135326: Restore support of integer-like objects with __index__() in random.getrandbits().

  • gh-135321: Raise a correct exception for values greater than 0x7fffffff for the BINSTRING opcode in the C implementation of pickle.

  • gh-135276: Backported bugfixes in zipfile.Path from zipp 3.23. Fixed .name, .stem and other basename-based properties on Windows when working with a zipfile on disk.

  • gh-134151: email: Fix TypeError in email.utils.decode_params() when sorting RFC 2231 continuations that contain an unnumbered section.

  • gh-134152: email: Fix parsing of email message ID with invalid domain.

  • gh-127081: Fix libc thread safety issues with os by replacing getlogin with getlogin_r re-entrant version.

  • gh-131884: Fix formatting issues in json.dump() when both indent and skipkeys are used.

Core and Builtins

  • gh-135171: Roll back changes to generator and list comprehensions that went into 3.13.4 to fix gh-127682, but which involved semantic and bytecode changes not appropriate for a bugfix release.

C API

  • gh-134989: Fix Py_RETURN_NONE, Py_RETURN_TRUE and Py_RETURN_FALSE macros in the limited C API 3.11 and older: don’t treat Py_None, Py_True and Py_False as immortal. Patch by Victor Stinner.

  • gh-134989: Implement PyObject_DelAttr() and PyObject_DelAttrString() as macros in the limited C API 3.12 and older. Patch by Victor Stinner.

Python 3.13.4 final

Release date: 2025-06-03

Windows

  • gh-130727: Fix a race in internal calls into WMI that can result in an “invalid handle” exception under high load. Patch by Chris Eibl.

  • gh-76023: Make os.path.realpath() ignore Windows error 1005 when in non-strict mode.

  • gh-133626: Ensures packages are not accidentally bundled into the traditional installer.

  • gh-133512: Add warnings to Python Launcher for Windows about use of subcommands belonging to the Python install manager.

Tests

  • gh-133744: Fix multiprocessing interrupt test. Add an event to synchronize the parent process with the child process: wait until the child process starts sleeping. Patch by Victor Stinner.

  • gh-133639: Fix TestPyReplAutoindent.test_auto_indent_default() doesn’t run input_code.

  • gh-133131: The iOS testbed will now select the most recently released “SE-class” device for testing if a device isn’t explicitly specified.

  • gh-109981: The test helper that counts the list of open file descriptors now uses the optimised /dev/fd approach on all Apple platforms, not just macOS. This avoids crashes caused by guarded file descriptors.

Security

  • gh-135034: Fixes multiple issues that allowed tarfile extraction filters (filter="data" and filter="tar") to be bypassed using crafted symlinks and hard links.

    Addresses CVE 2024-12718, CVE 2025-4138, CVE 2025-4330, and CVE 2025-4517.

  • gh-133767: Fix use-after-free in the “unicode-escape” decoder with a non-“strict” error handler.

  • gh-128840: Short-circuit the processing of long IPv6 addresses early in ipaddress to prevent excessive memory consumption and a minor denial-of-service.

Library

  • gh-134718: ast.dump() now only omits None and [] values if they are default values.

  • gh-128840: Fix parsing long IPv6 addresses with embedded IPv4 address.

  • gh-134696: Built-in HACL* and OpenSSL implementations of hash function constructors now correctly accept the same documented named arguments. For instance, md5() could be previously invoked as md5(data=data) or md5(string=string) depending on the underlying implementation but these calls were not compatible. Patch by Bénédikt Tran.

  • gh-134210: curses.window.getch() now correctly handles signals. Patch by Bénédikt Tran.

  • gh-80334: multiprocessing.freeze_support() now checks for work on any “spawn” start method platform rather than only on Windows.

  • gh-114177: Fix asyncio to not close subprocess pipes which would otherwise error out when the event loop is already closed.

  • gh-134152: Fixed UnboundLocalError that could occur during email header parsing if an expected trailing delimiter is missing in some contexts.

  • gh-62184: Remove import of C implementation of io.FileIO from Python implementation which has its own implementation

  • gh-133982: Emit RuntimeWarning in the Python implementation of io when the file-like object is not closed explicitly in the presence of multiple I/O layers.

  • gh-133890: The tarfile module now handles UnicodeEncodeError in the same way as OSError when cannot extract a member.

  • gh-134097: Fix interaction of the new REPL and -X showrefcount command line option.

  • gh-133889: The generated directory listing page in http.server.SimpleHTTPRequestHandler now only shows the decoded path component of the requested URL, and not the query and fragment.

  • gh-134098: Fix handling paths that end with a percent-encoded slash (%2f or %2F) in http.server.SimpleHTTPRequestHandler.

  • gh-134062: ipaddress: fix collisions in __hash__() for IPv4Network and IPv6Network objects.

  • gh-133745: In 3.13.3 we accidentally changed the signature of the asyncio create_task() family of methods and how it calls a custom task factory in a backwards incompatible way. Since some 3rd party libraries have already made changes to work around the issue that might break if we simply reverted the changes, we’re instead changing things to be backwards compatible with 3.13.2 while still supporting those workarounds for 3.13.3. In particular, the special-casing of name and context is back (until 3.14) and consequently eager tasks may still find that their name hasn’t been set before they execute their first yielding await.

  • gh-71253: Raise ValueError in open() if opener returns a negative file-descriptor in the Python implementation of io to match the C implementation.

  • gh-77057: Fix handling of invalid markup declarations in html.parser.HTMLParser.

  • gh-133489: random.getrandbits() can now generate more that 231 bits. random.randbytes() can now generate more that 256 MiB.

  • gh-133290: Fix attribute caching issue when setting ctypes._Pointer._type_ in the undocumented and deprecated ctypes.SetPointerType() function and the undocumented set_type() method.

  • gh-132876: ldexp() on Windows doesn’t round subnormal results before Windows 11, but should. Python’s math.ldexp() wrapper now does round them, so results may change slightly, in rare cases of very small results, on Windows versions before 11.

  • gh-133089: Use original timeout value for subprocess.TimeoutExpired when the func subprocess.run() is called with a timeout instead of sometimes a confusing partial remaining time out value used internally on the final wait().

  • gh-133009: xml.etree.ElementTree: Fix a crash in Element.__deepcopy__ when the element is concurrently mutated. Patch by Bénédikt Tran.

  • gh-132995: Bump the version of pip bundled in ensurepip to version 25.1.1

  • gh-132017: Fix error when pyrepl is suspended, then resumed and terminated.

  • gh-132673: Fix a crash when using _align_ = 0 and _fields_ = [] in a ctypes.Structure.

  • gh-132527: Include the valid typecode ‘w’ in the error message when an invalid typecode is passed to array.array.

  • gh-132439: Fix PyREPL on Windows: characters entered via AltGr are swallowed. Patch by Chris Eibl.

  • gh-132429: Fix support of Bluetooth sockets on NetBSD and DragonFly BSD.

  • gh-132106: QueueListener.start now raises a RuntimeError if the listener is already started.

  • gh-132417: Fix a NULL pointer dereference when a C function called using ctypes with restype py_object returns NULL.

  • gh-132385: Fix instance error suggestions trigger potential exceptions in object.__getattr__() in traceback.

  • gh-132308: A traceback.TracebackException now correctly renders the __context__ and __cause__ attributes from falsey Exception, and the exceptions attribute from falsey ExceptionGroup.

  • gh-132250: Fixed the SystemError in cProfile when locating the actual C function of a method raises an exception.

  • gh-132063: Prevent exceptions that evaluate as falsey (namely, when their __bool__ method returns False or their __len__ method returns 0) from being ignored by concurrent.futures.ProcessPoolExecutor and concurrent.futures.ThreadPoolExecutor.

  • gh-119605: Respect follow_wrapped for __init__() and __new__() methods when getting the class signature for a class with inspect.signature(). Preserve class signature after wrapping with warnings.deprecated(). Patch by Xuehai Pan.

  • gh-91555: Ignore log messages generated during handling of log messages, to avoid deadlock or infinite recursion. [NOTE: This change has since been reverted.]

  • gh-131434: Improve error reporting for incorrect format in time.strptime().

  • gh-131127: Systems using LibreSSL now successfully build.

  • gh-130999: Avoid exiting the new REPL and offer suggestions even if there are non-string candidates when errors occur.

  • gh-130941: Fix configparser.ConfigParser parsing empty interpolation with allow_no_value set to True.

  • gh-129098: Fix REPL traceback reporting when using compile() with an inexisting file. Patch by Bénédikt Tran.

  • gh-130631: http.cookiejar.join_header_words() is now more similar to the original Perl version. It now quotes the same set of characters and always quote values that end with "\n".

  • gh-129719: Fix missing socket.CAN_RAW_ERR_FILTER constant in the socket module on Linux systems. It was missing since Python 3.11.

  • gh-124096: Turn on virtual terminal mode and enable bracketed paste in REPL on Windows console. (If the terminal does not support bracketed paste, enabling it does nothing.)

  • gh-122559: Remove __reduce__() and __reduce_ex__() methods that always raise TypeError in the C implementation of io.FileIO, io.BufferedReader, io.BufferedWriter and io.BufferedRandom and replace them with default __getstate__() methods that raise TypeError. This restores fine details of behavior of Python 3.11 and older versions.

  • gh-122179: hashlib.file_digest() now raises BlockingIOError when no data is available during non-blocking I/O. Before, it added spurious null bytes to the digest.

  • gh-86155: html.parser.HTMLParser.close() no longer loses data when the <script> tag is not closed. Patch by Waylan Limberg.

  • gh-69426: Fix html.parser.HTMLParser to not unescape character entities in attribute values if they are followed by an ASCII alphanumeric or an equals sign.

  • bpo-44172: Keep a reference to original curses windows in subwindows so that the original window does not get deleted before subwindows.

IDLE

  • gh-112936: fix IDLE: no Shell menu item in single-process mode.

Documentation

Core and Builtins

  • gh-134908: Fix crash when iterating over lines in a text file on the free threaded build.

  • gh-127682: No longer call __iter__ twice in list comprehensions. This brings the behavior of list comprehensions in line with other forms of iteration

  • gh-134381: Fix RuntimeError when using a not-started threading.Thread after calling os.fork()

  • gh-128066: Fixes an edge case where PyREPL improperly threw an error when Python is invoked on a read only filesystem while trying to write history file entries.

  • gh-134100: Fix a use-after-free bug that occurs when an imported module isn’t in sys.modules after its initial import. Patch by Nico-Posada.

  • gh-133703: Fix hashtable in dict can be bigger than intended in some situations.

  • gh-132869: Fix crash in the free threading build when accessing an object attribute that may be concurrently inserted or deleted.

  • gh-132762: fromkeys() no longer loops forever when adding a small set of keys to a large base dict. Patch by Angela Liss.

  • gh-133543: Fix a possible memory leak that could occur when directly accessing instance dictionaries (__dict__) that later become part of a reference cycle.

  • gh-133516: Raise ValueError when constants True, False or None are used as an identifier after NFKC normalization.

  • gh-133441: Fix crash upon setting an attribute with a dict subclass. Patch by Victor Stinner.

  • gh-132942: Fix two races in the type lookup cache. This affected the free-threaded build and could cause crashes (apparently quite difficult to trigger).

  • gh-132713: Fix repr(list) race condition: hold a strong reference to the item while calling repr(item). Patch by Victor Stinner.

  • gh-132747: Fix a crash when calling __get__() of a method with a None second argument.

  • gh-132542: Update Thread.native_id after fork(2) to ensure accuracy. Patch by Noam Cohen.

  • gh-124476: Fix decoding from the locale encoding in the C.UTF-8 locale.

  • gh-131927: Compiler warnings originating from the same module and line number are now only emitted once, matching the behaviour of warnings emitted from user code. This can also be configured with warnings filters.

  • gh-127682: No longer call __iter__ twice when creating and executing a generator expression. Creating a generator expression from a non-interable will raise only when the generator expression is executed. This brings the behavior of generator expressions in line with other generators.

  • gh-131878: Handle uncaught exceptions in the main input loop for the new REPL.

  • gh-131878: Fix support of unicode characters with two or more codepoints on Windows in the new REPL.

  • gh-130804: Fix support of unicode characters on Windows in the new REPL.

  • gh-130070: Fixed an assertion error for exec() passed a string source and a non-None closure. Patch by Bartosz Sławecki.

  • gh-129958: Fix a bug that was allowing newlines inconsitently in format specifiers for single-quoted f-strings. Patch by Pablo Galindo.

C API

Build

  • gh-134923: Windows builds with profile-guided optimization enabled now use /GENPROFILE and /USEPROFILE instead of deprecated /LTCG: options.

  • gh-133183: iOS compiler shims now include IPHONEOS_DEPLOYMENT_TARGET in target triples, ensuring that SDK version minimums are honored.

  • gh-133167: Fix compilation process with --enable-optimizations and --without-docstrings.

  • gh-132649: The PClayout script now allows passing --include-tcltk on Windows ARM64.

  • gh-117088: AIX linker don’t support -h option, so avoid it through platform check

  • gh-132026: Fix use of undefined identifiers in platform triplet detection on MIPS Linux platforms.

Python 3.13.3 final

Release date: 2025-04-08

macOS

  • gh-124111: Update macOS installer to use Tcl/Tk 8.6.16.

  • gh-131423: Update macOS installer to use OpenSSL 3.0.16. Patch by Bénédikt Tran.

  • gh-131025: Update macOS installer to ship with SQLite 3.49.1.

  • gh-91132: Update macOS installer to use ncurses 6.5.

Windows

  • gh-131423: Update bundled version of OpenSSL to 3.0.16. The new build also disables uplink support, which may be relevant to embedders but has no impact on normal use.

  • gh-131025: Update Windows installer to ship with SQLite 3.49.1.

  • gh-131020: pylauncher correctly detects a BOM when searching for the shebang. Fix by Chris Eibl.

Tools/Demos

  • gh-131852: msgfmt no longer adds the POT-Creation-Date to generated .mo files for consistency with GNU msgfmt.

  • gh-85012: Correctly reset msgctxt when compiling messages in msgfmt.

  • gh-130025: The iOS testbed now correctly handles symlinks used as Python framework references.

Tests

  • gh-131050: test_ssl.test_dh_params is skipped if the underlying TLS library does not support finite-field ephemeral Diffie-Hellman.

  • gh-129200: Multiple iOS testbed runners can now be started at the same time without introducing an ambiguity over simulator ownership.

  • gh-130292: The iOS testbed will now run successfully on a machine that has not previously run Xcode tests (such as CI configurations).

  • gh-130293: The tests of terminal colorization are no longer sensitive to the value of the TERM variable in the testing environment.

  • gh-126332: Add unit tests for pyrepl.

Security

  • gh-131809: Update bundled libexpat to 2.7.1

  • gh-131261: Upgrade to libexpat 2.7.0

  • gh-127371: Avoid unbounded buffering for tempfile.SpooledTemporaryFile.writelines(). Previously, disk spillover was only checked after the lines iterator had been exhausted. This is now done after each line is written.

  • gh-121284: Fix bug in the folding of rfc2047 encoded-words when flattening an email message using a modern email policy. Previously when an encoded-word was too long for a line, it would be decoded, split across lines, and re-encoded. But commas and other special characters in the original text could be left unencoded and unquoted. This could theoretically be used to spoof header lines using a carefully constructed encoded-word if the resulting rendered email was transmitted or re-parsed.

Library

IDLE

  • gh-129873: Simplify displaying the IDLE doc by only copying the text section of idle.html to idlelib/help.html. Patch by Stan Ulbrych.

Documentation

Core and Builtins

  • gh-132011: Fix crash when calling list.append() as an unbound method.

  • gh-131998: Fix a crash when using an unbound method descriptor object in a function where a bound method descriptor was used.

  • gh-131988: Fix a performance regression that caused scaling bottlenecks in the free threaded build in 3.13.1 and 3.13.2.

  • gh-131719: Fix missing NULL check in _PyMem_FreeDelayed in free-threaded build.

  • gh-131670: Fix anext() failing on sync __anext__() raising an exception.

  • gh-131141: Fix data race in sys.monitoring instrumentation while registering callback.

  • gh-130932: Fix incorrect exception handling in _PyModule_IsPossiblyShadowing

  • gh-130851: Fix a crash in the free threading build when constructing a code object with co_consts that contains instances of types that are not otherwise generated by the bytecode compiler.

  • gh-130794: Fix memory leak in the free threaded build when resizing a shared list or dictionary from multiple short-lived threads.

  • gh-130775: Do not crash on negative column and end_column in ast locations.

  • gh-130382: Fix PyRefTracer_DESTROY not being sent from Python/ceval.c Py_DECREF().

  • gh-130618: Fix a bug that was causing UnicodeDecodeError or SystemError to be raised when using f-strings with lambda expressions with non-ASCII characters. Patch by Pablo Galindo

  • gh-130163: Fix possible crashes related to concurrent change and use of the sys module attributes.

  • gh-88887: Fixing multiprocessing Resource Tracker process leaking, usually observed when running Python as PID 1.

  • gh-130115: Fix an issue with thread identifiers being sign-extended on some platforms.

  • gh-128396: Fix a crash that occurs when calling locals() inside an inline comprehension that uses the same local variable as the outer frame scope where the variable is a free or cell var.

  • gh-116042: Fix location for SyntaxErrors of invalid escapes in the tokenizer. Patch by Pablo Galindo

  • gh-129983: Fix data race in compile_template in sre.c.

  • gh-129967: Fix a race condition in the free threading build when repr(set) is called concurrently with set.clear().

  • gh-129900: Fix return codes inside SystemExit not getting returned by the REPL.

  • gh-129732: Fixed a race in _Py_qsbr_reserve in the free threading build.

  • gh-129643: Fix thread safety of PyList_Insert() in free-threading builds.

  • gh-129668: Fix race condition when raising MemoryError in the free threaded build.

  • gh-129643: Fix thread safety of PyList_SetItem() in free-threading builds. Patch by Kumar Aditya.

  • gh-128714: Fix the potential races in get/set dunder methods __annotations__, __annotate__ and __type_params__ for function object, and add related tests.

  • gh-128632: Disallow __classdict__ as the name of a type parameter. Using this name would previously crash the interpreter in some circumstances.

  • gh-127953: The time to handle a LINE event in sys.monitoring (and sys.settrace) is now independent of the number of lines in the code object.

  • gh-125331: from __future__ import barry_as_FLUFL now works in more contexts, including when it is used in files, with the -c flag, and in the REPL when there are multiple statements on the same line. Previously, it worked only on subsequent lines in the REPL, and when the appropriate flags were passed directly to compile(). Patch by Pablo Galindo.

C API

Build

  • gh-131865: The DTrace build now properly passes the CC and CFLAGS variables to the dtrace command when utilizing SystemTap on Linux.

  • gh-131675: Fix mimalloc library builds for 32-bit ARM targets.

  • gh-130673: Fix potential KeyError when handling object sections during JIT building process.

  • gh-130740: Ensure that Python.h is included before stdbool.h unless pyconfig.h is included before or in some platform-specific contexts.

  • gh-129838: Don’t redefine _Py_NO_SANITIZE_UNDEFINED when compiling with a recent GCC version and undefined sanitizer enabled.

  • gh-129660: Drop test_embed from PGO training, whose contribution in recent versions is considered to be ignorable.

Python 3.13.2 final

Release date: 2025-02-04

macOS

  • gh-127592: Usage of the unified Apple System Log APIs was disabled when the minimum macOS version is earlier than 10.12.

Windows

  • gh-127353: Allow to force color output on Windows using environment variables. Patch by Andrey Efremov.

Tools/Demos

  • gh-129248: The iOS test runner now strips the log prefix from each line output by the test suite.

  • gh-128152: Fix a bug where Argument Clinic’s C pre-processor parser tried to parse pre-processor directives inside C comments. Patch by Erlend Aasland.

Tests

  • gh-127906: Test the limited C API in test_cppext. Patch by Victor Stinner.

  • gh-127637: Add tests for the dis command-line interface. Patch by Bénédikt Tran.

  • gh-126925: iOS test results are now streamed during test execution, and the deprecated xcresulttool is no longer used.

Security

  • gh-105704: When using urllib.parse.urlsplit() and urllib.parse.urlparse() host parsing would not reject domain names containing square brackets ([ and ]). Square brackets are only valid for IPv6 and IPvFuture hosts according to RFC 3986 Section 3.2.2.

  • gh-127655: Fixed the asyncio.selector_events._SelectorSocketTransport transport not pausing writes for the protocol when the buffer reaches the high water mark when using asyncio.WriteTransport.writelines().

  • gh-126108: Fix a possible NULL pointer dereference in PySys_AddWarnOptionUnicode().

  • gh-80222: Fix bug in the folding of quoted strings when flattening an email message using a modern email policy. Previously when a quoted string was folded so that it spanned more than one line, the surrounding quotes and internal escapes would be omitted. This could theoretically be used to spoof header lines using a carefully constructed quoted string if the resulting rendered email was transmitted or re-parsed.

  • gh-119511: Fix a potential denial of service in the imaplib module. When connecting to a malicious server, it could cause an arbitrary amount of memory to be allocated. On many systems this is harmless as unused virtual memory is only a mapping, but if this hit a virtual address size limit it could lead to a MemoryError or other process crash. On unusual systems or builds where all allocated memory is touched and backed by actual ram or storage it could’ve consumed resources doing so until similarly crashing.

Library

  • gh-129502: Unlikely errors in preparing arguments for ctypes callback are now handled in the same way as errors raised in the callback of in converting the result of the callback – using sys.unraisablehook() instead of sys.excepthook() and not setting sys.last_exc and other variables.

  • gh-129403: Corrected ValueError message for asyncio.Barrier and threading.Barrier.

  • gh-129409: Fix an integer overflow in the csv module when writing a data field larger than 2GB.

  • gh-118761: Improve import time of subprocess by lazy importing locale and signal. Patch by Taneli Hukkinen.

  • gh-129346: In sqlite3, handle out-of-memory when creating user-defined SQL functions.

  • gh-129061: Fix FORCE_COLOR and NO_COLOR when empty strings. Patch by Hugo van Kemenade.

  • gh-128550: Removed an incorrect optimization relating to eager tasks in asyncio.TaskGroup that resulted in cancellations being missed.

  • gh-128991: Release the enter frame reference within bdb callback

  • gh-128978: Fix a NameError in sysconfig.expand_makefile_vars(). Patch by Bénédikt Tran.

  • gh-128961: Fix a crash when setting state on an exhausted array.array iterator.

  • gh-128894: Fix traceback.TracebackException._format_syntax_error not to fail on exceptions with custom metadata.

  • gh-128916: Do not attempt to set SO_REUSEPORT on sockets of address families other than AF_INET and AF_INET6, as it is meaningless with these address families, and the call with fail with Linux kernel 6.12.9 and newer.

  • gh-128679: Fix tracemalloc.stop() race condition. Fix tracemalloc to support calling tracemalloc.stop() in one thread, while another thread is tracing memory allocations. Patch by Victor Stinner.

  • gh-128636: Fix PyREPL failure when os.environ is overwritten with an invalid value.

  • gh-128562: Fix possible conflicts in generated tkinter widget names if the widget class name ends with a digit.

  • gh-128498: Default to stdout isatty for color detection instead of stderr. Patch by Hugo van Kemenade.

  • gh-128552: Fix cyclic garbage introduced by asyncio.loop.create_task() and asyncio.TaskGroup.create_task() holding a reference to the created task if it is eager.

  • gh-128479: Fix asyncio.staggered.staggered_race() leaking tasks and issuing an unhandled exception.

  • gh-128400: Fix crash when using faulthandler.dump_traceback() while other threads are active on the free threaded build.

  • gh-88834: Unify the instance check for typing.Union and types.UnionType: Union now uses the instance checks against its parameters instead of the subclass checks.

  • gh-128302: Fix xml.dom.xmlbuilder.DOMEntityResolver.resolveEntity(), which was broken by the Python 3.0 transition.

  • gh-128302: Allow xml.dom.xmlbuilder.DOMParser.parse() to correctly handle xml.dom.xmlbuilder.DOMInputSource instances that only have a systemId attribute set.

  • gh-112064: Fix incorrect handling of negative read sizes in HTTPResponse.read. Patch by Yury Manushkin.

  • gh-58956: Fixed a frame reference leak in bdb.

  • gh-128131: Completely support random access of uncompressed unencrypted read-only zip files obtained by ZipFile.open.

  • gh-112328: enum.EnumDict can now be used without resorting to private API.

  • gh-127975: Avoid reusing quote types in ast.unparse() if not needed.

  • gh-128062: Revert the font of turtledemo’s menu bar to its default value and display the shortcut keys in the correct position.

  • gh-128014: Fix resetting the default window icon by passing default='' to the tkinter method wm_iconbitmap().

  • gh-115514: Fix exceptions and incomplete writes after asyncio._SelectorTransport is closed before writes are completed.

  • gh-41872: Fix quick extraction of module docstrings from a file in pydoc. It now supports docstrings with single quotes, escape sequences, raw string literals, and other Python syntax.

  • gh-127060: Set TERM environment variable to “dumb” to disable traceback colors in IDLE, since IDLE doesn’t understand ANSI escape sequences. Patch by Victor Stinner.

  • gh-126742: Fix support of localized error messages reported by dlerror(3) and gdbm_strerror in ctypes and dbm.gnu functions respectively. Patch by Bénédikt Tran.

  • gh-127873: When -E is set, only ignore PYTHON_COLORS and not FORCE_COLOR/NO_COLOR/TERM when colourising output. Patch by Hugo van Kemenade.

  • gh-127870: Detect recursive calls in ctypes _as_parameter_ handling. Patch by Victor Stinner.

  • gh-127847: Fix the position when doing interleaved seeks and reads in uncompressed, unencrypted zip files returned by zipfile.ZipFile.open().

  • gh-127732: The platform module now correctly detects Windows Server 2025.

  • gh-126821: macOS and iOS apps can now choose to redirect stdout and stderr to the system log during interpreter configuration.

  • gh-93312: Include <sys/pidfd.h> to get os.PIDFD_NONBLOCK constant. Patch by Victor Stinner.

  • gh-83662: Add missing __class_getitem__ method to the Python implementation of functools.partial(), to make it compatible with the C version. This is mainly relevant for alternative Python implementations like PyPy and GraalPy, because CPython will usually use the C-implementation of that function.

  • gh-127586: multiprocessing.pool.Pool now properly restores blocked signal handlers of the parent thread when creating processes via either spawn or forkserver.

  • gh-98188: Fix an issue in email.message.Message.get_payload() where data cannot be decoded if the Content Transfer Encoding mechanism contains trailing whitespaces or additional junk text. Patch by Hui Liu.

  • gh-127257: In ssl, system call failures that OpenSSL reports using ERR_LIB_SYS are now raised as OSError.

  • gh-127096: Do not recreate unnamed section on every read in configparser.ConfigParser. Patch by Andrey Efremov.

  • gh-127196: Fix crash when dict with keys in invalid encoding were passed to several functions in _interpreters module.

  • gh-126775: Make linecache.checkcache() thread safe and GC re-entrancy safe.

  • gh-126332: Fix _pyrepl crash when entering a double CTRL-Z on an overflowing line.

  • gh-126225: getopt and optparse are no longer marked as deprecated. There are legitimate reasons to use one of these modules in preference to argparse, and none of these modules are at risk of being removed from the standard library. Of the three, argparse remains the recommended default choice, unless one of the concerns noted at the top of the optparse module documentation applies.

  • gh-125553: Fix round-trip invariance for backslash continuations in tokenize.untokenize().

  • gh-123987: Fixed issue in NamespaceReader where a non-path item in a namespace path, such as a sentinel added by an editable installer, would break resource loading.

  • gh-123401: The http.cookies module now supports parsing obsolete RFC 850 date formats, in accordance with RFC 9110 requirements. Patch by Nano Zheng.

  • gh-122431: readline.append_history_file() now raises a ValueError when given a negative value.

  • gh-119257: Show tab completions menu below the current line, which results in less janky behaviour, and fixes a cursor movement bug. Patch by Daniel Hollas

Documentation

Core and Builtins

  • gh-129345: Fix null pointer dereference in syslog.openlog() when an audit hook raises an exception.

  • gh-129093: Fix f-strings such as f'{expr=}' sometimes not displaying the full expression when the expression contains !=.

  • gh-124363: Treat debug expressions in f-string as raw strings. Patch by Pablo Galindo

  • gh-128799: Add frame of except* to traceback when it wraps a naked exception.

  • gh-128078: Fix a SystemError when using anext() with a default tuple value. Patch by Bénédikt Tran.

  • gh-128717: Fix a crash when setting the recursion limit while other threads are active on the free threaded build.

  • gh-128330: Restore terminal control characters on REPL exit.

  • gh-128079: Fix a bug where except* does not properly check the return value of an ExceptionGroup’s split() function, leading to a crash in some cases. Now when split() returns an invalid object, except* raises a TypeError with the original raised ExceptionGroup object chained to it.

  • gh-128030: Avoid error from calling PyModule_GetFilenameObject on a non-module object when importing a non-existent symbol from a non-module object.

  • gh-127903: Objects/unicodeobject.c: fix a crash on DEBUG builds in _copy_characters when there is nothing to copy.

  • gh-127599: Fix statistics for increments of object reference counts (in particular, when a reference count was increased by more than 1 in a single operation).

  • gh-127651: When raising ImportError for missing symbols in from imports, use __file__ in the error message if __spec__.origin is not a location

  • gh-127582: Fix non-thread-safe object resurrection when calling finalizers and watcher callbacks in the free threading build.

  • gh-127434: The iOS compiler shims can now accept arguments with spaces.

  • gh-127536: Add missing locks around some list assignment operations in the free threading build.

  • gh-126862: Fix a possible overflow when a class inherits from an absurd number of super-classes. Reported by Valery Fedorenko. Patch by Bénédikt Tran.

  • gh-127349: Fixed the error when resizing terminal in Python REPL. Patch by Semyon Moroz.

  • gh-126076: Relocated objects such as tuple, bytes and str objects are properly tracked by tracemalloc and its associated hooks. Patch by Pablo Galindo.

C API

Build

  • gh-129539: Don’t redefine EX_OK when the system has the sysexits.h header.

  • gh-128472: Skip BOLT optimization of functions using computed gotos, fixing errors on build with LLVM 19.

  • gh-123925: Fix building the curses module on platforms with libncurses but without libncursesw.

  • gh-128321: Set LIBS instead of LDFLAGS when checking if sqlite3 library functions are available. This fixes the ordering of linked libraries during checks, which was incorrect when using a statically linked libsqlite3.

  • gh-127865: Fix build failure on systems without thread-locals support.

Python 3.13.1 final

Release date: 2024-12-03

macOS

  • gh-124448: Update bundled Tcl/Tk in macOS installer to 8.6.15.

Windows

  • gh-126911: Update credits command output.

  • gh-118973: Ensures the experimental free-threaded install includes the _tkinter module. The optional Tcl/Tk component must also be installed in order for the module to work.

  • gh-126497: Fixes venv failure due to missing redirector executables in experimental free-threaded installs.

  • gh-126074: Removed unnecessary DLLs from Windows embeddable package

  • gh-125315: Avoid crashing in platform due to slow WMI calls on some Windows machines.

  • gh-126084: Fix venvwlauncher to launch pythonw instead of python so no extra console window is created.

  • gh-125842: Fix a SystemError when sys.exit() is called with 0xffffffff on Windows.

  • gh-125550: Enable the Python Launcher for Windows to detect Python 3.14 installs from the Windows Store.

  • gh-124448: Updated bundled Tcl/Tk to 8.6.15.

Tools/Demos

  • gh-126807: Fix extraction warnings in pygettext.py caused by mistaking function definitions for function calls.

  • gh-126167: The iOS testbed was modified so that it can be used by third-party projects for testing purposes.

Tests

  • gh-126909: Fix test_os extended attribute tests to work on filesystems with 1 KiB xattr size limit.

  • gh-125041: Re-enable skipped tests for zlib on the s390x architecture: only skip checks of the compressed bytes, which can be different between zlib’s software implementation and the hardware-accelerated implementation.

  • gh-124295: Add translation tests to the argparse module.

Security

  • gh-126623: Upgrade libexpat to 2.6.4

  • gh-125140: Remove the current directory from sys.path when using PyREPL.

  • gh-122792: Changed IPv4-mapped ipaddress.IPv6Address to consistently use the mapped IPv4 address value for deciding properties. Properties which have their behavior fixed are is_multicast, is_reserved, is_link_local, is_global, and is_unspecified.

Library

  • gh-127321: pdb.set_trace() will not stop at an opcode that does not have an associated line number anymore.

  • gh-127303: Publicly expose EXACT_TOKEN_TYPES in token.__all__.

  • gh-123967: Fix faulthandler for trampoline frames. If the top-most frame is a trampoline frame, skip it. Patch by Victor Stinner.

  • gh-127182: Fix io.StringIO.__setstate__() crash, when None was passed as the first value.

  • gh-127217: Fix urllib.request.pathname2url() for paths starting with multiple slashes on Posix.

  • gh-127035: Fix shutil.which on Windows. Now it looks at direct match if and only if the command ends with a PATHEXT extension or X_OK is not in mode. Support extensionless files if “.” is in PATHEXT. Support PATHEXT extensions that end with a dot.

  • gh-122273: Support PyREPL history on Windows. Patch by devdanzin and Victor Stinner.

  • gh-127078: Fix issue where urllib.request.url2pathname() failed to discard an extra slash before a UNC drive in the URL path on Windows.

  • gh-126766: Fix issue where urllib.request.url2pathname() failed to discard any ‘localhost’ authority present in the URL.

  • gh-127065: Fix crash when calling a operator.methodcaller() instance from multiple threads in the free threading build.

  • gh-126997: Fix support of STRING and GLOBAL opcodes with non-ASCII arguments in pickletools. pickletools.dis() now outputs non-ASCII bytes in STRING, BINSTRING and SHORT_BINSTRING arguments as escaped (\xXX).

  • gh-126316: grp: Make grp.getgrall() thread-safe by adding a mutex. Patch by Victor Stinner.

  • gh-126618: Fix the representation of itertools.count objects when the count value is sys.maxsize.

  • gh-85168: Fix issue where urllib.request.url2pathname() and pathname2url() always used UTF-8 when quoting and unquoting file URIs. They now use the filesystem encoding and error handler.

  • gh-67877: Fix memory leaks when regular expression matching terminates abruptly, either because of a signal or because memory allocation fails.

  • gh-126789: Fixed the values of sysconfig.get_config_vars(), sysconfig.get_paths(), and their siblings when the site initialization happens after sysconfig has built a cache for sysconfig.get_config_vars().

  • gh-126188: Update bundled pip to 24.3.1

  • gh-126780: Fix os.path.normpath() for drive-relative paths on Windows.

  • gh-126766: Fix issue where urllib.request.url2pathname() failed to discard two leading slashes introducing an empty authority section.

  • gh-126727: locale.nl_langinfo(locale.ERA) now returns multiple era description segments separated by semicolons. Previously it only returned the first segment on platforms with Glibc.

  • gh-126699: Allow collections.abc.AsyncIterator to be a base for Protocols.

  • gh-126654: Fix crash when non-dict was passed to several functions in _interpreters module.

  • gh-104745: Limit starting a patcher (from unittest.mock.patch() or unittest.mock.patch.object()) more than once without stopping it

  • gh-126595: Fix a crash when instantiating itertools.count with an initial count of sys.maxsize on debug builds. Patch by Bénédikt Tran.

  • gh-120423: Fix issue where urllib.request.pathname2url() mishandled Windows paths with embedded forward slashes.

  • gh-126565: Improve performances of zipfile.Path.open() for non-reading modes.

  • gh-126505: Fix bugs in compiling case-insensitive regular expressions with character classes containing non-BMP characters: upper-case non-BMP character did was ignored and the ASCII flag was ignored when matching a character range whose upper bound is beyond the BMP region.

  • gh-117378: Fixed the multiprocessing "forkserver" start method forkserver process to correctly inherit the parent’s sys.path during the importing of multiprocessing.set_forkserver_preload() modules in the same manner as sys.path is configured in workers before executing work items.

    This bug caused some forkserver module preloading to silently fail to preload. This manifested as a performance degration in child processes when the sys.path was required due to additional repeated work in every worker.

    It could also have a side effect of "" remaining in sys.path during forkserver preload imports instead of the absolute path from os.getcwd() at multiprocessing import time used in the worker sys.path.

    The sys.path differences between phases in the child process could potentially have caused preload to import incorrect things from the wrong location. We are unaware of that actually having happened in practice.

  • gh-125679: The multiprocessing.Lock and multiprocessing.RLock repr values no longer say “unknown” on macOS.

  • gh-126476: Raise calendar.IllegalMonthError (now a subclass of IndexError) for calendar.month() when the input month is not correct.

  • gh-126489: The Python implementation of pickle no longer calls pickle.Pickler.persistent_id() for the result of persistent_id().

  • gh-126313: Fix an issue in curses.napms() when curses.initscr() has not yet been called. Patch by Bénédikt Tran.

  • gh-126303: Fix pickling and copying of os.sched_param objects.

  • gh-126138: Fix a use-after-free crash on asyncio.Task objects whose underlying coroutine yields an object that implements an evil __getattribute__(). Patch by Nico Posada.

  • gh-126220: Fix crash in cProfile.Profile and _lsprof.Profiler when their callbacks were directly called with 0 arguments.

  • gh-126212: Fix issue where urllib.request.pathname2url() and url2pathname() removed slashes from Windows DOS drive paths and URLs.

  • gh-126223: Raise a UnicodeEncodeError instead of a SystemError upon calling _interpreters.create() with an invalid Unicode character.

  • gh-126205: Fix issue where urllib.request.pathname2url() generated URLs beginning with four slashes (rather than two) when given a Windows UNC path.

  • gh-126105: Fix a crash in ast when the ast.AST._fields attribute is deleted.

  • gh-126106: Fixes a possible NULL pointer dereference in ssl.

  • gh-126080: Fix a use-after-free crash on asyncio.Task objects for which the underlying event loop implements an evil __getattribute__(). Reported by Nico-Posada. Patch by Bénédikt Tran.

  • gh-126083: Fixed a reference leak in asyncio.Task objects when reinitializing the same object with a non-None context. Patch by Nico Posada.

  • gh-125984: Fix use-after-free crashes on asyncio.Future objects for which the underlying event loop implements an evil __getattribute__(). Reported by Nico-Posada. Patch by Bénédikt Tran.

  • gh-125969: Fix an out-of-bounds crash when an evil asyncio.loop.call_soon() mutates the length of the internal callbacks list. Patch by Bénédikt Tran.

  • gh-125966: Fix a use-after-free crash in asyncio.Future.remove_done_callback(). Patch by Bénédikt Tran.

  • gh-125789: Fix possible crash when mutating list of callbacks returned by asyncio.Future._callbacks. It now always returns a new copy in C implementation _asyncio. Patch by Kumar Aditya.

  • gh-124452: Fix an issue in email.policy.EmailPolicy.header_source_parse() and email.policy.Compat32.header_source_parse() that introduced spurious leading whitespaces into header values when the header includes a newline character after the header name delimiter (:) and before the value.

  • gh-125884: Fixed the bug for pdb where it can’t set breakpoints on functions with certain annotations.

  • gh-125355: Fix several bugs in argparse.ArgumentParser.parse_intermixed_args().

    • The parser no longer changes temporarily during parsing.

    • Default values are not processed twice.

    • Required mutually exclusive groups containing positional arguments are now supported.

    • The missing arguments report now includes the names of all required optional and positional arguments.

    • Unknown options can be intermixed with positional arguments in parse_known_intermixed_args().

  • gh-125666: Avoid the exiting the interpreter if a null byte is given as input in the new REPL.

  • gh-125710: [Enum] fix hashable<->nonhashable comparisons for member values

  • gh-125631: Restore ability to set persistent_id and persistent_load attributes of instances of the Pickler and Unpickler classes in the pickle module.

  • gh-125378: Fixed the bug in pdb where after a multi-line command, an empty line repeats the first line of the multi-line command, instead of the full command.

  • gh-125682: Reject non-ASCII digits in the Python implementation of json.loads() conforming to the JSON specification.

  • gh-125660: Reject invalid unicode escapes for Python implementation of json.loads().

  • gh-125259: Fix the notes removal logic for errors thrown in enum initialization.

  • gh-125590: Allow FrameLocalsProxy to delete and pop if the key is not a fast variable.

  • gh-125519: Improve traceback if importlib.reload() is called with an object that is not a module. Patch by Alex Waygood.

  • gh-125451: Fix deadlock when concurrent.futures.ProcessPoolExecutor shuts down concurrently with an error when feeding a job to a worker process.

  • gh-125422: Fixed the bug where pdb and bdb can step into the bottom caller frame.

  • gh-100141: Fixed the bug where pdb will be stuck in an infinite loop when debugging an empty file.

  • gh-125115: Fixed a bug in pdb where arguments starting with - can’t be passed to the debugged script.

  • gh-53203: Fix time.strptime() for %c, %x and %X formats in many locales that use non-ASCII digits, like Persian, Burmese, Odia and Shan.

  • gh-125398: Fix the conversion of the VIRTUAL_ENV path in the activate script in venv when running in Git Bash for Windows.

  • gh-125316: Fix using functools.partial() as enum.Enum member. A FutureWarning with suggestion to use enum.member() is now emitted when the partial instance is used as an enum member.

  • gh-125245: Fix race condition when importing collections.abc, which could incorrectly return an empty module.

  • gh-125243: Fix data race when creating zoneinfo.ZoneInfo objects in the free threading build.

  • gh-125254: Fix a bug where ArgumentError includes the incorrect ambiguous option in argparse.

  • gh-125235: Keep tkinter TCL paths in venv pointing to base installation on Windows.

  • gh-61011: Fix inheritance of nested mutually exclusive groups from parent parser in argparse.ArgumentParser. Previously, all nested mutually exclusive groups lost their connection to the group containing them and were displayed as belonging directly to the parser.

  • gh-52551: Fix encoding issues in time.strftime(), the strftime() method of the datetime classes datetime, date and time and formatting of these classes. Characters not encodable in the current locale are now acceptable in the format string. Surrogate pairs and sequence of surrogatescape-encoded bytes are no longer recombinated. Embedded null character no longer terminates the format string.

  • gh-125118: Don’t copy arbitrary values to _Bool in the struct module.

  • gh-125069: Fix an issue where providing a pathlib.PurePath object as an initializer argument to a second PurePath object with a different parser resulted in arguments to the former object’s initializer being joined by the latter object’s parser.

  • gh-125096: If the PYTHON_BASIC_REPL environment variable is set, the site module no longer imports the _pyrepl module. Moreover, the site module now respects -E and -I command line options: ignore PYTHON_BASIC_REPL in this case. Patch by Victor Stinner.

  • gh-124969: Fix locale.nl_langinfo(locale.ALT_DIGITS) on platforms with glibc. Now it returns a string consisting of up to 100 semicolon-separated symbols (an empty string in most locales) on all Posix platforms. Previously it only returned the first symbol or an empty string.

  • gh-124960: Fix support for the barry_as_FLUFL future flag in the new REPL.

  • gh-124984: Fixed thread safety in ssl in the free-threaded build. OpenSSL operations are now protected by a per-object lock.

  • gh-124958: Fix refcycles in exceptions raised from asyncio.TaskGroup and the python implementation of asyncio.Future

  • gh-53203: Fix time.strptime() for %c and %x formats in many locales: Arabic, Bislama, Breton, Bodo, Kashubian, Chuvash, Estonian, French, Irish, Ge’ez, Gurajati, Manx Gaelic, Hebrew, Hindi, Chhattisgarhi, Haitian Kreyol, Japanese, Kannada, Korean, Marathi, Malay, Norwegian, Nynorsk, Punjabi, Rajasthani, Tok Pisin, Yoruba, Yue Chinese, Yau/Nungon and Chinese.

  • gh-124917: Allow calling os.path.exists() and os.path.lexists() with keyword arguments on Windows. Fixes a regression in 3.13.0.

  • gh-124653: Fix detection of the minimal Queue API needed by the logging module. Patch by Bénédikt Tran.

  • gh-124858: Fix reference cycles left in tracebacks in asyncio.open_connection() when used with happy_eyeballs_delay

  • gh-124390: Fixed AssertionError when using asyncio.staggered.staggered_race() with asyncio.eager_task_factory.

  • gh-124651: Properly quote template strings in venv activation scripts.

  • gh-116850: Fix argparse for namespaces with not directly writable dict (e.g. classes).

  • gh-58573: Fix conflicts between abbreviated long options in the parent parser and subparsers in argparse.

  • gh-124594: All asyncio REPL prompts run in the same context. Contributed by Bartosz Sławecki.

  • gh-61181: Fix support of choices with string value in argparse. Substrings of the specified string no longer considered valid values.

  • gh-80259: Fix argparse support of positional arguments with nargs='?', default=argparse.SUPPRESS and specified type.

  • gh-120378: Fix a crash related to an integer overflow in curses.resizeterm() and curses.resize_term().

  • gh-123884: Fixed bug in itertools.tee() handling of other tee inputs (a tee in a tee). The output now has the promised n independent new iterators. Formerly, the first iterator was identical (not independent) to the input iterator. This would sometimes give surprising results.

  • gh-58956: Fixed a bug in pdb where sometimes the breakpoint won’t trigger if it was set on a function which is already in the call stack.

  • gh-124345: argparse vim supports abbreviated single-dash long options separated by = from its value.

  • gh-104860: Fix disallowing abbreviation of single-dash long options in argparse with allow_abbrev=False.

  • gh-63143: Fix parsing mutually exclusive arguments in argparse. Arguments with the value identical to the default value (e.g. booleans, small integers, empty or 1-character strings) are no longer considered “not present”.

  • gh-72795: Positional arguments with nargs equal to '*' or argparse.REMAINDER are no longer required. This allows to use positional argument with nargs='*' and without default in mutually exclusive group and improves error message about required arguments.

  • gh-59317: Fix parsing positional argument with nargs equal to '?' or '*' if it is preceded by an option and another positional argument.

  • gh-53780: argparse now ignores the first "--" (double dash) between an option and command.

  • gh-124217: Add RFC 9637 reserved IPv6 block 3fff::/20 in ipaddress module.

  • gh-81691: Fix handling of multiple "--" (double dashes) in argparse. Only the first one has now been removed, all subsequent ones are now taken literally.

  • gh-123978: Remove broken time.thread_time() and time.thread_time_ns() on NetBSD.

  • gh-124008: Fix possible crash (in debug build), incorrect output or returning incorrect value from raw binary write() when writing to console on Windows.

  • gh-123935: Fix parent slots detection for dataclasses that inherit from classes with __dictoffset__.

  • gh-122765: Fix unbalanced quote errors occurring when activate.csh in venv was sourced with a custom prompt containing unpaired quotes or newlines.

  • gh-123370: Fix the canvas not clearing after running turtledemo clock.

  • gh-116810: Resolve a memory leak introduced in CPython 3.10’s ssl when the ssl.SSLSocket.session property was accessed. Speeds up read and write access to said property by no longer unnecessarily cloning session objects via serialization.

  • gh-120754: Update unbounded read calls in zipfile to specify an explicit size putting a limit on how much data they may read. This also updates handling around ZIP max comment size to match the standard instead of reading comments that are one byte too long.

  • gh-70764: Fixed an issue where inspect.getclosurevars() would incorrectly classify an attribute name as a global variable when the name exists both as an attribute name and a global variable.

  • gh-118289: posixpath.realpath() now raises NotADirectoryError when strict mode is enabled and a non-directory path with a trailing slash is supplied.

  • gh-119826: Always return an absolute path for os.path.abspath() on Windows.

  • gh-117766: Always use str() to print choices in argparse.

  • gh-101955: Fix SystemError when match regular expression pattern containing some combination of possessive quantifier, alternative and capture group.

  • gh-88110: Fixed multiprocessing.Process reporting a .exitcode of 1 even on success when using the "fork" start method while using a concurrent.futures.ThreadPoolExecutor.

  • gh-71936: Fix a race condition in multiprocessing.pool.Pool.

  • bpo-46128: Strip unittest.IsolatedAsyncioTestCase stack frames from reported stacktraces.

  • bpo-14074: Fix argparse metavar processing to allow positional arguments to have a tuple metavar.

IDLE

  • gh-122392: Increase currently inadequate vertical spacing for the IDLE browsers (path, module, and stack) on high-resolution monitors.

Documentation

  • gh-126622: Added stub pages for removed modules explaining their removal, where to find replacements, and linking to the last Python version that supported them. Contributed by Ned Batchelder.

  • gh-125277: Require Sphinx 7.2.6 or later to build the Python documentation. Patch by Adam Turner.

  • gh-124872: Added definitions for context, current context, and context management protocol, updated related definitions to be consistent, and expanded the documentation for contextvars.Context.

  • gh-125018: The importlib.metadata documentation now includes semantic cross-reference targets for the significant documented APIs. This means intersphinx references like importlib.metadata.version() will now work as expected.

  • gh-70870: Clarified the dual usage of the term “free variable” (both the formal meaning of any reference to names defined outside the local scope, and the narrower pragmatic meaning of nonlocal variables named in co_freevars).

  • gh-121277: Writers of CPython’s documentation can now use next as the version for the versionchanged, versionadded, deprecated directives.

  • gh-60712: Include the object type in the lists of documented types. Change by Furkan Onder and Martin Panter.

  • bpo-34008: The Py_Main() documentation moved from the “Very High Level API” section to the “Initialization and Finalization” section.

    Also make it explicit that we expect Py_Main to typically be called instead of Py_Initialize rather than after it (since Py_Main makes its own call to Py_Initialize). Document that calling both is supported but is version dependent on which settings will be applied correctly.

Core and Builtins

  • gh-113841: Fix possible undefined behavior division by zero in complex’s _Py_c_pow().

  • gh-127020: Fix a crash in the free threading build when PyCode_GetCode(), PyCode_GetVarnames(), PyCode_GetCellvars(), or PyCode_GetFreevars() were called from multiple threads at the same time.

  • gh-126980: Fix __buffer__() of bytearray crashing when READ or WRITE are passed as flags.

  • gh-126881: Fix crash in finalization of dtoa state. Patch by Kumar Aditya.

  • gh-126341: Now ValueError is raised instead of SystemError when trying to iterate over a released memoryview object.

  • gh-126688: Fix a crash when calling os.fork() on some operating systems, including SerenityOS.

  • gh-126066: Fix importlib to not write an incomplete .pyc files when a ulimit or some other operating system mechanism is preventing the write to go through fully.

  • gh-126312: Fix crash during garbage collection on an object frozen by gc.freeze() on the free-threaded build.

  • gh-126139: Provide better error location when attempting to use a future statement with an unknown future feature.

  • gh-126018: Fix a crash in sys.audit() when passing a non-string as first argument and Python was compiled in debug mode.

  • gh-125942: On Android, the errors setting of sys.stdout was changed from surrogateescape to backslashreplace.

  • gh-125859: Fix a crash in the free threading build when gc.get_objects() or gc.get_referrers() is called during an in-progress garbage collection.

  • gh-125703: Correctly honour tracemalloc hooks in specialized Py_DECREF paths. Patch by Pablo Galindo

  • gh-125593: Use color to highlight error locations in traceback from exception group

  • gh-125444: Fix illegal instruction for older Arm architectures. Patch by Diego Russo, testing by Ross Burton.

  • gh-124375: Fix a crash in the free threading build when the GC runs concurrently with a new thread starting.

  • gh-125221: Fix possible race condition when calling __reduce_ex__() for the first time in the free threading build.

  • gh-125038: Fix crash when iterating over a generator expression after direct changes on gi_frame.f_locals. Patch by Mikhail Efimov.

  • gh-123378: Fix a crash in the __str__() method of UnicodeError objects when the UnicodeError.start and UnicodeError.end values are invalid or out-of-range. Patch by Bénédikt Tran.

  • gh-116510: Fix a crash caused by immortal interned strings being shared between sub-interpreters that use basic single-phase init. In that case, the string can be used by an interpreter that outlives the interpreter that created and interned it. For interpreters that share obmalloc state, also share the interned dict with the main interpreter.

  • gh-122878: Use the pager binary, if available (e.g. on Debian and derivatives), to display REPL help().

  • gh-124188: Fix reading and decoding a line from the source file witn non-UTF-8 encoding for syntax errors raised in the compiler.

  • gh-123930: Improve the error message when a script shadowing a module from the standard library causes ImportError to be raised during a “from” import. Similarly, improve the error message when a script shadowing a third party module attempts to “from” import an attribute from that third party module while still initialising.

  • gh-122907: Building with HAVE_DYNAMIC_LOADING now works as well as it did in 3.12. Existing deficiences will be addressed separately. (See https://github.com/python/cpython/issues/122950.)

  • gh-118950: Fix bug where SSLProtocol.connection_lost wasn’t getting called when OSError was thrown on writing to socket.

  • gh-113570: Fixed a bug in reprlib.repr where it incorrectly called the repr method on shadowed Python built-in types.

  • gh-109746: If _thread.start_new_thread() fails to start a new thread, it deletes its state from interpreter and thus avoids its repeated cleanup on finalization.

C API

  • gh-126554: Fix error handling in ctypes.CDLL objects which could result in a crash in rare situations.

  • gh-125608: Fix a bug where dictionary watchers (e.g., PyDict_Watch()) on an object’s attribute dictionary (__dict__) were not triggered when the object’s attributes were modified.

  • bpo-34008: Added Py_IsInitialized to the list of APIs that are safe to call before the interpreter is initialized, and updated the embedding tests to cover it.

Build

  • gh-123877: Set wasm32-wasip1 as the WASI target. The old wasm32-wasi target is deprecated so it can be used for an eventual WASI 1.0.

  • gh-89640: Hard-code float word ordering as little endian on WASM.

  • gh-125940: The Android build now supports 16 KB page sizes.

  • gh-89640: Improve detection of float word ordering on Linux when link-time optimizations are enabled.

  • gh-125269: Fix detection of whether -latomic is needed when cross-compiling CPython using the configure script.

  • gh-121634: Allow for specifying the target compile triple for WASI.

  • gh-122578: Use WASI SDK 24 for testing.

  • gh-115382: Fix cross compile failures when the host and target SOABIs match.

Python 3.13.0 final

Release date: 2024-10-07

Core and Builtins

  • gh-125008: Fix tokenize.untokenize() producing invalid syntax for double braces preceded by certain escape characters.

  • gh-124871: Fix compiler bug (in some versions of 3.13) where an assertion fails during reachability analysis.

Python 3.13.0 release candidate 3

Release date: 2024-10-01

macOS

  • gh-123797: Check for runtime availability of ptsname_r function on macos.

Windows

  • gh-124609: Fix _Py_ThreadId for Windows builds using MinGW. Patch by Tony Roberts.

  • gh-124254: Ensures experimental free-threaded binaries remain installed when updating.

  • gh-123915: Ensure that Tools\msi\buildrelease.bat uses different directories for AMD64 and ARM64 builds.

Tests

  • gh-124378: Updated test_ttk to pass with Tcl/Tk 8.6.15.

Library

IDLE

  • gh-112938: Fix uninteruptable hang when Shell gets rapid continuous output.

  • gh-120104: Fix padding in config and search dialog windows in IDLE.

Documentation

  • gh-124720: Update “Using Python on a Mac” section of the “Python Setup and Usage” document and include information on installing free-threading support.

  • gh-116622: Add an Android platform guide, and flag modules not available on Android.

Core and Builtins

  • gh-124567: Revert the incremental GC (in 3.13), since it’s not clear the benefits outweigh the costs at this point.

  • gh-124642: Fixed scalability issue in free-threaded builds for lock-free reads from dictionaries in multi-threaded scenarios

  • gh-116510: Fix a bug that can cause a crash when sub-interpreters use “basic” single-phase extension modules. Shared objects could refer to PyGC_Head nodes that had been freed as part of interpreter cleanup.

  • gh-124547: When deallocating an object with inline values whose __dict__ is still live: if memory allocation for the inline values fails, clear the dictionary. Prevents an interpreter crash.

  • gh-124513: Fix a crash in FrameLocalsProxy constructor: check the number of arguments. Patch by Victor Stinner.

  • gh-124442: Fix nondeterminism in compilation by sorting the value of __static_attributes__. Patch by kp2pml30.

  • gh-123856: Fix PyREPL failure when a keyboard interrupt is triggered after using a history search

  • gh-65961: Document the deprecation of setting and using __package__ and __cached__.

  • gh-124027: Support <page up>, <page down>, and <delete> keys in the Python REPL when $TERM is set to vt100.

  • gh-77894: Fix possible crash in the garbage collector when it tries to break a reference loop containing a memoryview object. Now a memoryview object can only be cleared if there are no buffers that refer it.

  • gh-123339: Setting the __module__ attribute for a class now removes the __firstlineno__ item from the type’s dict, so they will no longer be inconsistent.

C API

  • gh-124160: Fix crash when importing modules containing state and single-phase initialization in a subinterpreter.

  • gh-123880: Fixed a bug that prevented circular imports of extension modules that use single-phase initialization.

Build

  • gh-124487: Windows builds now use Windows 8.1 as their API baseline (installation already required Windows 8.1).

  • gh-124043: Building using --with-trace-refs is (temporarily) disallowed when the GIL is disabled.

Python 3.13.0 release candidate 2

Release date: 2024-09-06

macOS

  • gh-123418: Updated macOS installer build to use OpenSSL 3.0.15.

Windows

  • gh-123418: Updated Windows build to use OpenSSL 3.0.15.

  • gh-122573: The Windows build of CPython now requires 3.10 or newer.

  • gh-100256: mimetypes no longer fails when it encounters an inaccessible registry key.

  • gh-79846: Makes ssl.create_default_context() ignore invalid certificates in the Windows certificate store

Tools/Demos

  • gh-123418: Update GitHub CI workflows to use OpenSSL 3.0.15 and multissltests to use 3.0.15, 3.1.7, and 3.2.3.

Tests

  • gh-119727: Add --single-process command line option to Python test runner (regrtest). Patch by Victor Stinner.

  • gh-101525: Skip test_gdb if the binary is relocated by BOLT. Patch by Donghee Na.

Security

  • gh-123678: Upgrade libexpat to 2.6.3

  • gh-121285: Remove backtracking from tarfile header parsing for hdrcharset, PAX, and GNU sparse headers.

Library

IDLE

  • gh-120083: Add explicit black IDLE Hovertip foreground color needed for recent macOS. Fixes Sonoma showing unreadable white on pale yellow. Patch by John Riggles.

Core and Builtins

  • gh-120221: asyncio REPL is now again properly recognizing KeyboardInterrupts. Display of exceptions raised in secondary threads is fixed.

  • gh-119310: Allow the new interactive shell to read history files written with the editline library that use unicode-escaped entries. Patch by aorcajo and Łukasz Langa.

  • gh-123572: Fix key mappings for various F-keys in Windows for the new REPL. Patch by devdanzin

  • gh-119034: Change <page up> and <page down> keys of the Python REPL to history search forward/backward. Patch by Victor Stinner.

  • gh-123545: Fix a double decref in rare cases on experimental JIT builds.

  • gh-123484: Fix _Py_DebugOffsets for long objects to be relative to the start of the object rather than the start of a subobject.

  • gh-123344: Add AST optimizations for type parameter defaults.

  • gh-123321: Prevent Parser/myreadline race condition from segfaulting on multi-threaded use. Patch by Bar Harel and Amit Wienner.

  • gh-123177: Fix a bug causing stray prompts to appear in the middle of wrapped lines in the new REPL.

  • gh-122982: Extend the deprecation period for bool inversion (~) by two years.

  • gh-123275: Support -X gil=1 and PYTHON_GIL=1 on non-free-threaded builds.

  • gh-123177: Deactivate line wrap in the Apple Terminal via a ANSI escape code. Patch by Pablo Galindo

  • gh-123229: Fix valgrind warning by initializing the f-string buffers to 0 in the tokenizer. Patch by Pablo Galindo

  • gh-122298: Restore printout of GC stats when gc.set_debug(gc.DEBUG_STATS) is called. This featue was accidentally removed when implementing incremental GC.

  • gh-121804: Correctly show error locations when a SyntaxError is raised in the basic REPL. Patch by Sergey B Kirpichev.

  • gh-123142: Fix too-wide source location in exception tracebacks coming from broken iterables in comprehensions.

  • gh-123048: Fix a bug where pattern matching code could emit a JUMP_FORWARD with no source location.

  • gh-123123: Fix displaying SyntaxError exceptions covering multiple lines. Patch by Pablo Galindo

  • gh-123083: Fix a potential use-after-free in STORE_ATTR_WITH_HINT.

  • gh-123022: Fix crash in free-threaded build when calling Py_Initialize() from a non-main thread.

  • gh-122888: Fix crash on certain calls to str() with positional arguments of the wrong type. Patch by Jelle Zijlstra.

  • gh-116622: Fix Android stdout and stderr messages being truncated or lost.

  • gh-122527: Fix a crash that occurred when a PyStructSequence was deallocated after its type’s dictionary was cleared by the GC. The type’s tp_basicsize now accounts for non-sequence fields that aren’t included in the Py_SIZE of the sequence.

  • gh-122445: Add only fields which are modified via self.* to __static_attributes__.

  • gh-98442: Fix too wide source locations of the cleanup instructions of a with statement.

  • gh-93691: Fix source locations of instructions generated for with statements.

  • gh-120097: FrameLocalsProxy now subclasses collections.abc.Mapping and can be matched as a mapping in match statements

C API

Build

  • gh-123418: Updated Android build to use OpenSSL 3.0.15.

  • gh-123297: Propagate the value of LDFLAGS to LDCXXSHARED in sysconfig. Patch by Pablo Galindo

  • gh-116622: Rename build variable MODULE_LDFLAGS back to LIBPYTHON, as it’s used by package build systems (e.g. Meson).

  • gh-118943: Fix an issue where the experimental JIT could be built several times by the make regen-all target, leading to possible race conditions on heavily parallelized builds.

  • gh-118943: Fix a possible race condition affecting parallel builds configured with --enable-experimental-jit, in which FileNotFoundError could be caused by another process already moving jit_stencils.h.new to jit_stencils.h.

Python 3.13.0 release candidate 1

Release date: 2024-07-31

Tests

Security

  • gh-122133: Authenticate the socket connection for the socket.socketpair() fallback on platforms where AF_UNIX is not available like Windows.

    Patch by Gregory P. Smith <greg@krypto.org> and Seth Larson <seth@python.org>. Reported by Ellie <el@horse64.org>

  • gh-121957: Fixed missing audit events around interactive use of Python, now also properly firing for python -i, as well as for python -m asyncio. The events in question are cpython.run_stdin and cpython.run_startup.

Library

IDLE

  • gh-122482: Change About IDLE to direct users to discuss.python.org instead of the now unused idle-dev email and mailing list.

Core and Builtins

  • gh-116090: Fix an issue in JIT builds that prevented some for loops from correctly firing RAISE monitoring events.

  • gh-122208: Dictionary watchers now only deliver the PyDict_EVENT_ADDED event when the insertion is in a known good state to succeed.

  • gh-122300: Preserve AST nodes for f-string with single-element format specifiers. Patch by Pablo Galindo

  • gh-120906: frame.f_locals now supports arbitrary hashable objects as keys.

  • gh-122029: Emit c_call events in sys.setprofile() when a PyMethodObject pointing to a PyCFunction is called.

  • gh-122026: Fix a bug that caused the tokenizer to not correctly identify mismatched parentheses inside f-strings in some situations. Patch by Pablo Galindo

  • gh-118934: Make PyEval_GetLocals return borrowed reference

C API

  • gh-116622: Make PyObject_Print work around a bug in Android and OpenBSD which prevented it from throwing an exception when trying to write to a read-only stream.

  • gh-121489: Export private _PyBytes_Join() again.

Build

Python 3.13.0 beta 4

Release date: 2024-07-18

Tests

  • gh-121084: Fix test_typing random leaks. Clear typing ABC caches when running tests for refleaks (-R option): call _abc_caches_clear() on typing abstract classes and their subclasses. Patch by Victor Stinner.

  • gh-121160: Add a test for readline.set_history_length(). Note that this test may fail on readline libraries.

  • gh-121200: Fix test_expanduser_pwd2() of test_posixpath. Call getpwnam() to get pw_dir, since it can be different than getpwall() pw_dir. Patch by Victor Stinner.

  • gh-121188: When creating the JUnit XML file, regrtest now escapes characters which are invalid in XML, such as the chr(27) control character used in ANSI escape sequences. Patch by Victor Stinner.

Library

  • gh-57141: The shallow argument to filecmp.dircmp (new in Python 3.13) is now keyword-only.

  • gh-121245: Simplify handling of the history file in site.register_readline() helper. The CAN_USE_PYREPL variable now will be initialized, when imported. Patch by Sergey B Kirpichev.

  • gh-121332: Fix constructor of ast nodes with custom _attributes. Previously, passing custom attributes would raise a DeprecationWarning. Passing arguments to the constructor that are not in _fields or _attributes remains deprecated. Patch by Jelle Zijlstra.

  • gh-121279: Avoid NameError for the warnings module when accessing the depracated atributes of the importlib.abc module.

  • gh-121245: Fix a bug in the handling of the command history of the new REPL that caused the history file to be wiped at REPL exit.

  • gh-87744: Fix waitpid race while calling send_signal() in asyncio. Patch by Kumar Aditya.

  • gh-121018: Fixed other issues where argparse.ArgumentParser did not honor exit_on_error=False.

  • gh-120678: Fix regression in the new REPL that meant that globals from files passed using the -i argument would not be included in the REPL’s global namespace. Patch by Alex Waygood.

  • gh-120782: Fix wrong references of the datetime types after reloading the module.

  • gh-120713: datetime.datetime.strftime() now 0-pads years with less than four digits for the format specifiers %Y and %G on Linux. Patch by Ben Hsing

  • gh-117983: Defer the threading import in importlib.util until lazy loading is used.

  • gh-119189: When using the ** operator or pow() with Fraction as the base and an exponent that is not rational, a float, or a complex, the fraction is no longer converted to a float.

  • gh-118714: Allow restart in post-mortem debugging of pdb. Removed restart message when the user quits pdb from post-mortem mode.

  • gh-105623: Fix performance degradation in logging.handlers.RotatingFileHandler. Patch by Craig Robson.

IDLE

  • gh-78889: Stop Shell freezes by blocking user access to non-method sys.stdout.shell attributes, which are all private.

Documentation

Core and Builtins

  • gh-121860: Fix crash when rematerializing a managed dictionary after it was deleted.

  • gh-121814: Fixed the SegFault when PyEval_SetTrace() is used with no Python frame on stack.

  • gh-121295: Fix PyREPL console getting into a blocked state after interrupting a long paste

  • gh-121794: Fix bug in free-threaded Python where a resurrected object could lead to a negative ref count assertion failure.

  • gh-121657: Improve the SyntaxError message if the user tries to use yield from outside a function.

  • gh-121609: Fix pasting of characters containing unicode character joiners in the new REPL. Patch by Marta Gomez Macias

  • gh-117482: Unexpected slot wrappers are no longer created for builtin static types in subinterpreters.

  • gh-121499: Fix a bug affecting how multi-line history was being rendered in the new REPL after interacting with the new screen cache. Patch by Pablo Galindo

  • gh-121497: Fix a bug that was preventing the REPL to correctly respect the history when an input hook was set. Patch by Pablo Galindo

  • gh-121012: Tier 2 execution now ensures that list iterators remain exhausted, once they become exhausted.

  • gh-121439: Allow tuples of length 20 in the freelist to be reused.

  • gh-121368: Fix race condition in _PyType_Lookup in the free-threaded build due to a missing memory fence. This could lead to _PyType_Lookup returning incorrect results on arm64.

  • gh-121130: Fix f-strings with debug expressions in format specifiers. Patch by Pablo Galindo

  • gh-121115: PyLong_AsNativeBytes() no longer uses __index__() methods by default. The Py_ASNATIVEBYTES_ALLOW_INDEX flag has been added to allow it.

C API

Build

  • gh-120371: Support WASI SDK 22 by explicitly skipping functions that are just stubs in wasi-libc.

  • gh-121731: Fix mimalloc compile error on GNU/Hurd

  • gh-121487: Fix deprecation warning for ATOMIC_VAR_INIT in mimalloc.

  • gh-121467: Fix a Makefile bug that prevented mimalloc header files from being installed.

  • gh-121103: On POSIX systems, excluding macOS framework installs, the lib directory for the free-threaded build now includes a “t” suffix to avoid conflicts with a co-located default build installation.

  • gh-120831: The default minimum iOS version was increased to 13.0.

  • gh-113565: Improve curses and curses.panel dependency checks in configure.

Python 3.13.0 beta 3

Release date: 2024-06-27

Core and Builtins

  • gh-120838: Py_Finalize() and Py_FinalizeEx() now always run with the main interpreter active.

  • gh-113433: Subinterpreters now get cleaned up automatically during runtime finalization.

  • gh-119462: Make sure that invariants of type versioning are maintained: * Superclasses always have their version number assigned before subclasses * The version tag is always zero if the tag is not valid. * The version tag is always non-zero if the tag is valid.

  • gh-120437: Fix _CHECK_STACK_SPACE optimization problems introduced in gh-118322.

  • gh-120722: Correctly set the bytecode position on return instructions within lambdas. Patch by Jelle Zijlstra.

  • gh-120367: Fix bug where compiler creates a redundant jump during pseudo-op replacement. Can only happen with a synthetic AST that has a try on the same line as the instruction following the exception handler.

  • gh-113993: Strings interned with sys.intern() are again garbage-collected when no longer used, as per the documentation. Strings interned with the C function PyUnicode_InternInPlace() are still immortal. Internals of the string interning mechanism have been changed. This may affect performance and identities of str objects.

  • gh-120384: Fix an array out of bounds crash in list_ass_subscript, which could be invoked via some specificly tailored input: including concurrent modification of a list object, where one thread assigns a slice and another clears it.

  • gh-120367: Fix crash in compiler on code with redundant NOPs and JUMPs which show up after exception handlers are moved to the end of the code.

  • gh-120380: Fix Python implementation of pickle.Pickler for bytes and bytearray objects when using protocol version 5. Patch by Bénédikt Tran.

  • gh-120400: Support Linux perf profiler to see Python calls on RISC-V architecture.

  • gh-120221: Deliver real signals on Ctrl-C and Ctrl-Z in the new REPL. Patch by Pablo Galindo

  • gh-120346: Respect PYTHON_BASIC_REPL when running in interative inspect mode (python -i). Patch by Pablo Galindo

  • gh-93691: Fix source locations of instructions generated for the iterator of a for statement.

  • gh-120198: Fix a crash when multiple threads read and write to the same __class__ of an object concurrently.

  • gh-120298: Fix use-after free in list_richcompare_impl which can be invoked via some specificly tailored evil input.

  • gh-119666: Fix a compiler crash in the case where two comprehensions in class scope both reference __class__.

  • gh-120225: Fix crash in compiler on empty block at end of exception handler.

  • gh-119933: Improve SyntaxError messages for invalid expressions in a type parameters bound, a type parameter constraint tuple or a default type parameter. Patch by Bénédikt Tran.

  • bpo-24766: Fix handling of doc argument to subclasses of property.

Library

Build

  • gh-120671: Fix failing configure tests due to a missing space when appending to CFLAGS.

  • gh-120602: Correctly handle LLVM installs with LLVM_VERSION_SUFFIX when building with --enable-experimental-jit.

  • gh-120326: On Windows, fix build error when --disable-gil and --experimental-jit options are combined.

  • gh-120291: Make the python-config shell script compatible with non-bash shells.

C API

  • gh-120642: Remove the private _Py_CODEUNIT type from the public C API. The internal pycore_code.h header should now be used to get this internal type. Patch by Victor Stinner.

  • gh-120858: PyDict_Next() no longer locks the dictionary in the free-threaded build. The locking needs to be done by the caller around the entire iteration loop.

  • gh-120642: Remove the following unstable functions:

    • PyUnstable_Replace_Executor()

    • PyUnstable_SetOptimizer()

    • PyUnstable_GetOptimizer()

    • PyUnstable_GetExecutor()

    • PyUnstable_Optimizer_NewCounter()

    • PyUnstable_Optimizer_NewUOpOptimizer()

    Patch by Victor Stinner.

  • gh-119344: The critical section API is now public as part of the non-limited C API.

  • gh-118789: Add PyUnstable_Object_ClearWeakRefsNoCallbacks(), which clears weakrefs without calling their callbacks.

  • gh-117511: Make the PyMutex public in the non-limited C API.

Python 3.13.0 beta 2

Release date: 2024-06-05

Security

  • gh-118773: Fixes creation of ACLs in os.mkdir() on Windows to work correctly on non-English machines.

  • gh-118486: os.mkdir() on Windows now accepts mode of 0o700 to restrict the new directory to the current user. This fixes CVE 2024-4030 affecting tempfile.mkdtemp() in scenarios where the base temporary directory is more permissive than the default.

Core and Builtins

  • gh-119724: Reverted improvements to error messages for elif/else statements not matching any valid statements, which made in hard to locate the syntax errors inside those elif/else blocks.

  • gh-119842: Honor PyOS_InputHook() in the new REPL. Patch by Pablo Galindo

  • gh-119821: Fix execution of annotation scopes within classes when globals is set to a non-dict. Patch by Jelle Zijlstra.

  • gh-119548: Add a clear command to the REPL. Patch by Pablo Galindo

  • gh-111999: Fix the signature of str.format_map().

  • gh-119560: An invalid assert in beta 1 has been removed. The assert would fail if PyState_FindModule() was used in an extension module’s init function before the module def had been initialized.

  • gh-119369: Fix deadlock during thread deletion in free-threaded build, which could occur when the GIL was enabled at runtime.

  • gh-119525: Fix deadlock involving _PyType_Lookup() cache in the free-threaded build when the GIL is dynamically enabled at runtime.

  • gh-119311: Fix bug where names are unexpectedly mangled in the bases of generic classes.

  • gh-119395: Fix bug where names appearing after a generic class are mangled as if they are in the generic class.

  • gh-119213: Non-builtin modules built with argument clinic were crashing if used in a subinterpreter before the main interpreter. The objects that were causing the problem by leaking between interpreters carelessly have been fixed.

  • gh-119011: Fixes type.__type_params__ to return an empty tuple instead of a descriptor.

  • gh-118692: Avoid creating unnecessary StopIteration instances for monitoring.

  • gh-119049: Fix displaying the source line for warnings created by the C API if the warnings module had not yet been imported.

  • gh-118844: Fix build failures when configuring with both --disable-gil and --enable-experimental-jit.

  • gh-118921: Add copy() method for FrameLocalsProxy which returns a snapshot dict for local variables.

  • gh-117657: Fix data races on the field that stores a pointer to the interpreter’s main thread that occur in free-threaded builds.

  • gh-118561: Fix race condition in free-threaded build where list.extend() could expose uninitialised memory to concurrent readers.

  • gh-117195: Avoid assertion failure for debug builds when calling object.__sizeof__(1)

Library

  • gh-119819: Fix regression to allow logging configuration with multiprocessing queue types.

  • gh-117142: The ctypes module may now be imported in all subinterpreters, including those that have their own GIL.

  • gh-118835: Fix _pyrepl crash when using custom prompt with ANSI escape codes.

  • gh-117398: The _datetime module (C implementation for datetime) now supports being imported in multiple interpreters.

  • gh-89727: Fix issue with shutil.rmtree() where a RecursionError is raised on deep directory trees.

  • gh-89727: Partially fix issue with shutil.rmtree() where a RecursionError is raised on deep directory trees. A recursion error is no longer raised when rmtree.avoids_symlink_attacks is false.

  • gh-119118: Fix performance regression in the tokenize module by caching the line token attribute and calculating the column offset more efficiently.

  • gh-89727: Fix issue with os.fwalk() where a RecursionError was raised on deep directory trees by adjusting the implementation to be iterative instead of recursive.

  • gh-119588: zipfile.Path.is_symlink now assesses if the given path is a symlink.

  • gh-119555: Catch SyntaxError from compile() in the runsource() method of the InteractiveColoredConsole. Patch by Sergey B Kirpichev.

  • gh-113892: Now, the method sock_connect of asyncio.ProactorEventLoop raises a ValueError if given socket is not in non-blocking mode, as well as in other loop implementations.

  • gh-119443: The interactive REPL no longer runs with from __future__ import annotations enabled. Patch by Jelle Zijlstra.

  • gh-117398: Objects in the datetime C-API are now all statically allocated, which means better memory safety, especially when the module is reloaded. This should be transparent to users.

  • gh-118894: