• Removed an unnecessary check from _fsspec._make_async that would raise an exception when creating a read-only store backed by a local file system with auto_mkdir set to False. (:issue:`3193`)
• Add missing import for AsyncFileSystemWrapper for _make_async in _fsspec.py (:issue:`3195`)

• Add zarr.storage.FsspecStore.from_mapper() so that zarr.open() supports stores of type fsspec.mapping.FSMap. (:issue:`2774`)
• Implemented move for LocalStore and ZipStore. This allows users to move the store to a different root path. (:issue:`3021`)
• Added ~zarr.errors.GroupNotFoundError, which is raised when attempting to open a group that does not exist. (:issue:`3066`)
• Adds fill_value to the list of attributes displayed in the output of the AsyncArray.info() method. (:issue:`3081`)
• Use :py:func:`numpy.zeros` instead of :py:func:`np.full` for a performance speedup when creating a zarr.core.buffer.NDBuffer with fill_value=0. (:issue:`3082`)
• Port more stateful testing actions from Icechunk. (:issue:`3130`)
• Adds a with_read_only convenience method to the Store abstract base class (raises NotImplementedError) and implementations to the MemoryStore, ObjectStore, LocalStore, and FsspecStore classes. (:issue:`3138`)

• Ignore stale child metadata when reconsolidating metadata. (:issue:`2921`)

• For Zarr format 2, allow fixed-length string arrays to be created without automatically inserting a Vlen-UT8 codec in the array of filters. Fixed-length string arrays do not need this codec. This change fixes a regression where fixed-length string arrays created with Zarr Python 3 could not be read with Zarr Python 2.18. (:issue:`3100`)

• When creating arrays without explicitly specifying a chunk size using zarr.create and other array creation routines, the chunk size will now set automatically instead of defaulting to the data shape. For large arrays this will result in smaller default chunk sizes. To retain previous behaviour, explicitly set the chunk shape to the data shape.

  This fix matches the existing chunking behaviour of zarr.save_array and zarr.api.asynchronous.AsyncArray.create. (:issue:`3103`)

• When zarr.save has an argument path=some/path/ and multiple arrays in args, the path resulted in some/path/some/path due to using the path argument twice while building the array path. This is now fixed. (:issue:`3127`)

• Fix zarr.open default for argument mode when store is read_only (:issue:`3128`)

• Suppress FileNotFoundError when deleting non-existent keys in the obstore adapter.

  When writing empty chunks (i.e. chunks where all values are equal to the array's fill value) to a zarr array, zarr will delete those chunks from the underlying store. For zarr arrays backed by the obstore adapter, this will potentially raise a FileNotFoundError if the chunk doesn't already exist. Since whether or not a delete of a non-existing object raises an error depends on the behavior of the underlying store, suppressing the error in all cases results in consistent behavior across stores, and is also what zarr seems to expect from the store. (:issue:`3140`)

• Trying to open a StorePath/Array with mode='r' when the store is not read-only creates a read-only copy of the store. (:issue:`3156`)

• Added a print_debug_info function for bug reports. (:issue:`2913`)

• Fix a bug that prevented the number of initialized chunks being counted properly. (:issue:`2862`)

• Fixed sharding with GPU buffers. (:issue:`2978`)

• Fix structured dtype fill value serialization for consolidated metadata (:issue:`2998`)

• It is now possible to specify no compressor when creating a zarr format 2 array. This can be done by passing compressor=None to the various array creation routines.

  The default behaviour of automatically choosing a suitable default compressor remains if the compressor argument is not given. To reproduce the behaviour in previous zarr-python versions when compressor=None was passed, pass compressor='auto' instead. (:issue:`3039`)

• Fixed the typing of dimension_names arguments throughout so that it now accepts iterables that contain None alongside str. (:issue:`3045`)

• Using various functions to open data with mode='a' no longer deletes existing data in the store. (:issue:`3062`)

• Internally use typesize constructor parameter for :class:`numcodecs.blosc.Blosc` to improve compression ratios back to the v2-package levels. (:issue:`2962`)

• Specifying the memory order of Zarr format 2 arrays using the order keyword argument has been fixed. (:issue:`2950`)

• :issue:`2972`, :issue:`3027`, :issue:`3049`

• Add experimental ObjectStore storage class based on obstore. (:issue:`1661`)
• Add zarr.from_array using concurrent streaming of source data (:issue:`2622`)

• 0-dimensional arrays are now returning a scalar. Therefore, the return type of __getitem__ changed to NDArrayLikeOrScalar. This change is to make the behavior of 0-dimensional arrays consistent with numpy scalars. (:issue:`2718`)
• Fix fill_value serialization for NaN in ArrayV2Metadata and add property-based testing of round-trip serialization (:issue:`2802`)
• Fixes ConsolidatedMetadata serialization of nan, inf, and -inf to be consistent with the behavior of ArrayMetadata. (:issue:`2996`)

• Updated the 3.0 migration guide to include the removal of "." syntax for getting group members. (:issue:`2991`, :issue:`2997`)

• Define a new versioning policy based on Effective Effort Versioning. This replaces the old Semantic Versioning-based policy. (:issue:`2924`, :issue:`2910`)
• Make warning filters in the tests more specific, so warnings emitted by tests added in the future are more likely to be caught instead of ignored. (:issue:`2714`)
• Avoid an unnecessary memory copy when writing Zarr to a local file (:issue:`2944`)

• Restore functionality of del z.attrs['key'] to actually delete the key. (:issue:`2908`)

• Fixed a bug where StorePath creation would not apply standard path normalization to the path parameter, which led to the creation of arrays and groups with invalid keys. (:issue:`2850`)
• Prevent update_attributes calls from deleting old attributes (:issue:`2870`)

• :issue:`2796`

• Adds functions for concurrently creating multiple arrays and groups. (:issue:`2665`)

• Fixed a bug where ArrayV2Metadata could save filters as an empty array. (:issue:`2847`)
• Fix a bug when setting values of a smaller last chunk. (:issue:`2851`)

• :issue:`2828`

• Improves performance of FsspecStore.delete_dir for remote filesystems supporting concurrent/batched deletes, e.g., s3fs. (:issue:`2661`)
• Added :meth:`zarr.config.enable_gpu` to update Zarr's configuration to use GPUs. (:issue:`2751`)
• Avoid reading chunks during writes where possible. :issue:`757` (:issue:`2784`)
• :py:class:`LocalStore` learned to delete_dir. This makes array and group deletes more efficient. (:issue:`2804`)
• Add zarr.testing.strategies.array_metadata to generate ArrayV2Metadata and ArrayV3Metadata instances. (:issue:`2813`)
• Add arbitrary shards to Hypothesis strategy for generating arrays. (:issue:`2822`)

• Fixed bug with Zarr using device memory, instead of host memory, for storing metadata when using GPUs. (:issue:`2751`)
• The array returned by zarr.empty and an empty zarr.core.buffer.cpu.NDBuffer will now be filled with the specified fill value, or with zeros if no fill value is provided. This fixes a bug where Zarr format 2 data with no fill value was written with un-predictable chunk sizes. (:issue:`2755`)
• Fix zip-store path checking for stores with directories listed as files. (:issue:`2758`)
• Use removeprefix rather than replace when removing filename prefixes in FsspecStore.list (:issue:`2778`)
• Enable automatic removal of needs release notes with labeler action (:issue:`2781`)
• Use the proper label config (:issue:`2785`)
• Alters the behavior of create_array to ensure that any groups implied by the array's name are created if they do not already exist. Also simplifies the type signature for any function that takes an ArrayConfig-like object. (:issue:`2795`)
• Enitialise empty chunks to the default fill value during writing and add default fill values for datetime, timedelta, structured, and other (void* fixed size) data types (:issue:`2799`)
• Ensure utf8 compliant strings are used to construct numpy arrays in property-based tests (:issue:`2801`)
• Fix pickling for ZipStore (:issue:`2807`)
• Update numcodecs to not overwrite codec configuration ever. Closes :issue:`2800`. (:issue:`2811`)
• Fix fancy indexing (e.g. arr[5, [0, 1]]) with the sharding codec (:issue:`2817`)

• Added new user guide on :ref:`user-guide-gpu`. (:issue:`2751`)

• Test getsize() and getsize_prefix() in StoreTests. (:issue:`2693`)
• Test that a ValueError is raised for invalid byte range syntax in StoreTests. (:issue:`2693`)
• Separate instantiating and opening a store in StoreTests. (:issue:`2693`)
• Add a test for using Stores as a context managers in StoreTests. (:issue:`2693`)
• Implemented LogingStore.open(). (:issue:`2693`)
• LoggingStore is now a generic class. (:issue:`2693`)
• Change StoreTest's test_store_repr, test_store_supports_writes, test_store_supports_partial_writes, and test_store_supports_listing to to be implemented using @abstractmethod, rather raising NotImplementedError. (:issue:`2693`)
• Test the error raised for invalid buffer arguments in StoreTests. (:issue:`2693`)
• Test that data can be written to a store that's not yet open using the store.set method in StoreTests. (:issue:`2693`)
• Adds a new function init_array for initializing an array in storage, and refactors create_array to use init_array. create_array takes two new parameters: data, an optional array-like object, and write_data, a bool which defaults to True. If data is given to create_array, then the dtype and shape attributes of data are used to define the corresponding attributes of the resulting Zarr array. Additionally, if data given and write_data is True, then the values in data will be written to the newly created array. (:issue:`2761`)

• Wrap sync fsspec filesystems with AsyncFileSystemWrapper. (:issue:`2533`)
• Added backwards compatibility for Zarr format 2 structured arrays. (:issue:`2681`)
• Update equality for LoggingStore and WrapperStore such that 'other' must also be a LoggingStore or WrapperStore respectively, rather than only checking the types of the stores they wrap. (:issue:`2693`)
• Ensure that ZipStore is open before getting or setting any values. (:issue:`2693`)
• Use stdout rather than stderr as the default stream for LoggingStore. (:issue:`2693`)
• Match the errors raised by read only stores in StoreTests. (:issue:`2693`)
• Fixed ZipStore to make sure the correct attributes are saved when instances are pickled. This fixes a previous bug that prevent using ZipStore with a ProcessPoolExecutor. (:issue:`2762`)
• Updated the optional test dependencies to include botocore and fsspec. (:issue:`2768`)
• Fixed the fsspec tests to skip if botocore is not installed. Previously they would have failed with an import error. (:issue:`2768`)
• Optimize full chunk writes. (:issue:`2782`)

• Changed the machinery for creating changelog entries. Now individual entries should be added as files to the changes directory in the zarr-python repository, instead of directly to the changelog file. (:issue:`2736`)

• Created a type alias ChunkKeyEncodingLike to model the union of ChunkKeyEncoding instances and the dict form of the parameters of those instances. ChunkKeyEncodingLike should be used by high-level functions to provide a convenient way for creating ChunkKeyEncoding objects. (:issue:`2763`)

• Implement zarr.from_array using concurrent streaming (:issue:`2622`).

• Fixes order argument for Zarr format 2 arrays (:issue:`2679`).
• Fixes a bug that prevented reading Zarr format 2 data with consolidated metadata written using zarr-python version 2 (:issue:`2694`).
• Ensure that compressor=None results in no compression when writing Zarr format 2 data (:issue:`2708`).
• Fix for empty consolidated metadata dataset: backwards compatibility with Zarr-Python 2 (:issue:`2695`).

• Add v3.0.0 release announcement banner (:issue:`2677`).
• Quickstart guide alignment with V3 API (:issue:`2697`).
• Fix doctest failures related to numcodecs 0.15 (:issue:`2727`).

• Removed some unnecessary files from the source distribution to reduce its size. (:issue:`2686`).
• Enable codecov in GitHub actions (:issue:`2682`).
• Speed up hypothesis tests (:issue:`2650`).
• Remove multiple imports for an import name (:issue:`2723`).

3.0.0 is a new major release of Zarr-Python, with many breaking changes. See the :ref:`v3 migration guide` for a listing of what's changed.

Normal release note service will resume with further releases in the 3.0.0 series.

Release notes for the zarr-python 2.x and 1.x releases can be found here: https://zarr.readthedocs.io/en/support-v2/release.html