For a complete changelog, see:

* https://github.com/yaml/pyyaml/commits/
* https://bitbucket.org/xi/pyyaml/commits/

5.4.1 (2021-01-20)

* https://github.com/yaml/pyyaml/pull/480 -- Fix stub compat with older pyyaml versions that may unwittingly load it

5.4 (2021-01-19)

* https://github.com/yaml/pyyaml/pull/407 -- Build modernization, remove distutils, fix metadata, build wheels, CI to GHA
* https://github.com/yaml/pyyaml/pull/472 -- Fix for CVE-2020-14343, moves arbitrary python tags to UnsafeLoader
* https://github.com/yaml/pyyaml/pull/441 -- Fix memory leak in implicit resolver setup
* https://github.com/yaml/pyyaml/pull/392 -- Fix py2 copy support for timezone objects
* https://github.com/yaml/pyyaml/pull/378 -- Fix compatibility with Jython

5.3.1 (2020-03-18)

* https://github.com/yaml/pyyaml/pull/386 -- Prevents arbitrary code execution during python/object/new constructor

5.3 (2020-01-06)

* https://github.com/yaml/pyyaml/pull/290 -- Use `is` instead of equality for comparing with `None`
* https://github.com/yaml/pyyaml/pull/270 -- Fix typos and stylistic nit
* https://github.com/yaml/pyyaml/pull/309 -- Fix up small typo
* https://github.com/yaml/pyyaml/pull/161 -- Fix handling of __slots__
* https://github.com/yaml/pyyaml/pull/358 -- Allow calling add_multi_constructor with None
* https://github.com/yaml/pyyaml/pull/285 -- Add use of safe_load() function in README
* https://github.com/yaml/pyyaml/pull/351 -- Fix reader for Unicode code points over 0xFFFF
* https://github.com/yaml/pyyaml/pull/360 -- Enable certain unicode tests when maxunicode not > 0xffff
* https://github.com/yaml/pyyaml/pull/359 -- Use full_load in yaml-highlight example
* https://github.com/yaml/pyyaml/pull/244 -- Document that PyYAML is implemented with Cython
* https://github.com/yaml/pyyaml/pull/329 -- Fix for Python 3.10
* https://github.com/yaml/pyyaml/pull/310 -- Increase size of index, line, and column fields
* https://github.com/yaml/pyyaml/pull/260 -- Remove some unused imports
* https://github.com/yaml/pyyaml/pull/163 -- Create timezone-aware datetimes when parsed as such
* https://github.com/yaml/pyyaml/pull/363 -- Add tests for timezone

5.2 (2019-12-02)
------------------

* Repair incompatibilities introduced with 5.1. The default Loader was changed,
  but several methods like add_constructor still used the old default
  https://github.com/yaml/pyyaml/pull/279 -- A more flexible fix for custom tag constructors
  https://github.com/yaml/pyyaml/pull/287 -- Change default loader for yaml.add_constructor
  https://github.com/yaml/pyyaml/pull/305 -- Change default loader for add_implicit_resolver, add_path_resolver
* Make FullLoader safer by removing python/object/apply from the default FullLoader
  https://github.com/yaml/pyyaml/pull/347 -- Move constructor for object/apply to UnsafeConstructor
* Fix bug introduced in 5.1 where quoting went wrong on systems with sys.maxunicode <= 0xffff
  https://github.com/yaml/pyyaml/pull/276 -- Fix logic for quoting special characters
* Other PRs:
  https://github.com/yaml/pyyaml/pull/280 -- Update CHANGES for 5.1

5.1.2 (2019-07-30)
------------------

* Re-release of 5.1 with regenerated Cython sources to build properly for Python 3.8b2+

5.1.1 (2019-06-05)
------------------

* Re-release of 5.1 with regenerated Cython sources to build properly for Python 3.8b1

5.1 (2019-03-13)
----------------

* https://github.com/yaml/pyyaml/pull/35 -- Some modernization of the test running
* https://github.com/yaml/pyyaml/pull/42 -- Install tox in a virtualenv
* https://github.com/yaml/pyyaml/pull/45 -- Allow colon in a plain scalar in a flow context
* https://github.com/yaml/pyyaml/pull/48 -- Fix typos
* https://github.com/yaml/pyyaml/pull/55 -- Improve RepresenterError creation
* https://github.com/yaml/pyyaml/pull/59 -- Resolves #57, update readme issues link
* https://github.com/yaml/pyyaml/pull/60 -- Document and test Python 3.6 support
* https://github.com/yaml/pyyaml/pull/61 -- Use Travis CI built in pip cache support
* https://github.com/yaml/pyyaml/pull/62 -- Remove tox workaround for Travis CI
* https://github.com/yaml/pyyaml/pull/63 -- Adding support to Unicode characters over codepoint 0xffff
* https://github.com/yaml/pyyaml/pull/75 -- add 3.12 changelog
* https://github.com/yaml/pyyaml/pull/76 -- Fallback to Pure Python if Compilation fails
* https://github.com/yaml/pyyaml/pull/84 -- Drop unsupported Python 3.3
* https://github.com/yaml/pyyaml/pull/102 -- Include license file in the generated wheel package
* https://github.com/yaml/pyyaml/pull/105 -- Removed Python 2.6 & 3.3 support
* https://github.com/yaml/pyyaml/pull/111 -- Remove commented out Psyco code
* https://github.com/yaml/pyyaml/pull/129 -- Remove call to `ord` in lib3 emitter code
* https://github.com/yaml/pyyaml/pull/149 -- Test on Python 3.7-dev
* https://github.com/yaml/pyyaml/pull/158 -- Support escaped slash in double quotes "\/"
* https://github.com/yaml/pyyaml/pull/175 -- Updated link to pypi in release announcement
* https://github.com/yaml/pyyaml/pull/181 -- Import Hashable from collections.abc
* https://github.com/yaml/pyyaml/pull/194 -- Reverting https://github.com/yaml/pyyaml/pull/74
* https://github.com/yaml/pyyaml/pull/195 -- Build libyaml on travis
* https://github.com/yaml/pyyaml/pull/196 -- Force cython when building sdist
* https://github.com/yaml/pyyaml/pull/254 -- Allow to turn off sorting keys in Dumper (2)
* https://github.com/yaml/pyyaml/pull/256 -- Make default_flow_style=False
* https://github.com/yaml/pyyaml/pull/257 -- Deprecate yaml.load and add FullLoader and UnsafeLoader classes
* https://github.com/yaml/pyyaml/pull/261 -- Skip certain unicode tests when maxunicode not > 0xffff
* https://github.com/yaml/pyyaml/pull/263 -- Windows Appveyor build

3.13 (2018-07-05)
-----------------

* Resolved issues around PyYAML working in Python 3.7.

3.12 (2016-08-28)
-----------------

* Wheel packages for Windows binaries.
* Adding an implicit resolver to a derived loader should not affect the base loader.
* Uniform representation for OrderedDict? across different versions of Python.
* Fixed comparison to None warning.

3.11 (2014-03-26)
-----------------

* Source and binary distributions are rebuilt against the latest
  versions of Cython and LibYAML.

3.10 (2011-05-30)
-----------------

* Do not try to build LibYAML bindings on platforms other than CPython
  (Thank to olt(at)bogosoft(dot)com).
* Clear cyclic references in the parser and the emitter
  (Thank to kristjan(at)ccpgames(dot)com).
* Dropped support for Python 2.3 and 2.4.

3.09 (2009-08-31)
-----------------

* Fixed an obscure scanner error not reported when there is
  no line break at the end of the stream (Thank to Ingy).
* Fixed use of uninitialized memory when emitting anchors with
  LibYAML bindings (Thank to cegner(at)yahoo-inc(dot)com).
* Fixed emitting incorrect BOM characters for UTF-16 (Thank to
  Valentin Nechayev)
* Fixed the emitter for folded scalars not respecting the preferred
  line width (Thank to Ingy).
* Fixed a subtle ordering issue with emitting '%TAG' directives
  (Thank to Andrey Somov).
* Fixed performance regression with LibYAML bindings.


3.08 (2008-12-31)
-----------------

* Python 3 support (Thank to Erick Tryzelaar).
* Use Cython instead of Pyrex to build LibYAML bindings.
* Refactored support for unicode and byte input/output streams.


3.07 (2008-12-29)
-----------------

* The emitter learned to use an optional indentation indicator
  for block scalar; thus scalars with leading whitespaces
  could now be represented in a literal or folded style.
* The test suite is now included in the source distribution.
  To run the tests, type 'python setup.py test'.
* Refactored the test suite: dropped unittest in favor of
  a custom test appliance.
* Fixed the path resolver in CDumper.
* Forced an explicit document end indicator when there is
  a possibility of parsing ambiguity.
* More setup.py improvements: the package should be usable
  when any combination of setuptools, Pyrex and LibYAML
  is installed.
* Windows binary packages are built against LibYAML-0.1.2.
* Minor typos and corrections (Thank to Ingy dot Net
  and Andrey Somov).


3.06 (2008-10-03)
-----------------

* setup.py checks whether LibYAML is installed and if so, builds
  and installs LibYAML bindings.  To force or disable installation
  of LibYAML bindings, use '--with-libyaml' or '--without-libyaml'
  respectively.
* The source distribution includes compiled Pyrex sources so
  building LibYAML bindings no longer requires Pyrex installed.
* 'yaml.load()' raises an exception if the input stream contains
  more than one YAML document.
* Fixed exceptions produced by LibYAML bindings.
* Fixed a dot '.' character being recognized as !!float.
* Fixed Python 2.3 compatibility issue in constructing !!timestamp values.
* Windows binary packages are built against the LibYAML stable branch.
* Added attributes 'yaml.__version__' and  'yaml.__with_libyaml__'.


3.05 (2007-05-13)
-----------------

* Windows binary packages were built with LibYAML trunk.
* Fixed a bug that prevent processing a live stream of YAML documents in
  timely manner (Thanks edward(at)sweetbytes(dot)net).
* Fixed a bug when the path in add_path_resolver contains boolean values
  (Thanks jstroud(at)mbi(dot)ucla(dot)edu).
* Fixed loss of microsecond precision in timestamps
  (Thanks edemaine(at)mit(dot)edu).
* Fixed loading an empty YAML stream.
* Allowed immutable subclasses of YAMLObject.
* Made the encoding of the unicode->str conversion explicit so that
  the conversion does not depend on the default Python encoding.
* Forced emitting float values in a YAML compatible form.


3.04 (2006-08-20)
-----------------

* Include experimental LibYAML bindings.
* Fully support recursive structures.
* Sort dictionary keys.  Mapping node values are now represented
  as lists of pairs instead of dictionaries.  No longer check
  for duplicate mapping keys as it didn't work correctly anyway.
* Fix invalid output of single-quoted scalars in cases when a single
  quote is not escaped when preceded by whitespaces or line breaks.
* To make porting easier, rewrite Parser not using generators.
* Fix handling of unexpected block mapping values.
* Fix a bug in Representer.represent_object: copy_reg.dispatch_table
  was not correctly handled.
* Fix a bug when a block scalar is incorrectly emitted in the simple
  key context.
* Hold references to the objects being represented.
* Make Representer not try to guess !!pairs when a list is represented.
* Fix timestamp constructing and representing.
* Fix the 'N' plain scalar being incorrectly recognized as !!bool.


3.03 (2006-06-19)
-----------------

* Fix Python 2.5 compatibility issues.
* Fix numerous bugs in the float handling.
* Fix scanning some ill-formed documents.
* Other minor fixes.


3.02 (2006-05-15)
-----------------

* Fix win32 installer.  Apparently bdist_wininst does not work well
  under Linux.
* Fix a bug in add_path_resolver.
* Add the yaml-highlight example.  Try to run on a color terminal:
  `python yaml_hl.py <any_document.yaml`.


3.01 (2006-05-07)
-----------------

* Initial release.  The version number reflects the codename
  of the project (PyYAML 3000) and differentiates it from
  the abandoned PyYaml module.