Fails to read v2 consolidated metadata if .zattrs is not present

[nbren12]

Zarr version

v3

Numcodecs version

n/a

Python Version

3.12

Operating System

Linux

Installation

pip

Description

I have a zarr v2 dataset with no group level .zattrs. I have consolidated the metadata to .zmetadata. This dataset opens successfully in zarr==2 but v3 is not using the consolidated metadata, and openings hangs indefinitely as it lists every key.

The error is caused by this line of code:

zarr-python/src/zarr/core/group.py

Line 576 in 0c154c3

v2_consolidated_metadata.pop(".zattrs", None)

This seems like a bug. It will fail if the .zattrs is not present, but the v2 spec states

The “.zattrs” key does not have to be present, and if it is absent the attributes should be treated as empty.

Steps to reproduce

.

Additional output

No response

[jhamman]

Thanks @nbren12 for the report! Are you using 3.0.1? I think we had a related fix for this from #2694.

[nbren12]

Thanks Joe. Sorry for the duplicate issue. zarr==3.0.1 works like a charm.