• Potentially breaking: The converters raise StructureHandlerNotFoundError more eagerly (on hook creation, instead of on hook use). This helps surfacing problems with missing hooks sooner. See Migrations for steps to restore legacy behavior.
  (#577)
• Add a Migrations page, with instructions on migrating changed behavior for each version.
  (#577)
• typing.Self is now supported in attrs classes, dataclasses, TypedDicts and the dict NamedTuple factories. See typing.Self for details.
  (#299 #627)
• PEP 695 type aliases can now be used with BaseConverter.register_structure_hook and BaseConverter.register_unstructure_hook. Previously, they required the use of BaseConverter.register_structure_hook_func (which is still supported).
  (#647)
• Expose cattrs.cols.mapping_unstructure_factory through cattrs.cols.
• Some defaultdicts are now supported by default, and
  cattrs.cols.is_defaultdict and cattrs.cols.defaultdict_structure_factory are exposed through cattrs.cols.
  (#519 #588)
• Generic PEP 695 type aliases are now supported.
  (#611 #618)
• The tagged union strategy now also supports type aliases of unions.
  (#649)
• Converter.copy and BaseConverter.copy are correctly annotated as returning Self.
  (#644)
• Many preconf converters (bson, stdlib JSON, cbor2, msgpack, msgspec, orjson, ujson) skip unstructuring int and str enums, leaving them to the underlying libraries to handle with greater efficiency.
  (#598)
• The msgspec JSON preconf converter now handles dataclasses with private attributes more efficiently.
  (#624)
• Literals containing enums are now unstructured properly, and their unstructuring is greatly optimized in the bson, stdlib JSON, cbor2, msgpack, msgspec, orjson and ujson preconf converters.
  (#598)
• Preconf converters now handle dictionaries with literal keys properly.
  (#599)
• Structuring TypedDicts from invalid inputs now properly raises a ClassValidationError.
  (#615 #616)
• cattrs.strategies.include_subclasses now properly works with generic parent classes.
  (#649)
• Replace cattrs.gen.MappingStructureFn with cattrs.SimpleStructureHook.
• Python 3.13 is now supported.
  (#543 #547)
• Python 3.8 is no longer supported, as it is end-of-life. Use previous versions on this Python version.
  (#591)
• Change type of Converter.__init__.unstruct_collection_overrides from Callable to Mapping[type, UnstructureHook]
  (#594).
• Adopt the Contributor Covenant Code of Conduct (just like attrs).