Missing _zstd module in Python 3.14 image

[Etienne-gh]

Python 3.14 standard library now includes zstd compression. However, the Python 3.14 image does not include needed zstd module:

docker run --rm -it --entrypoint python --platform linux/amd64 public.ecr.aws/lambda/python:3.14 -c "from compression import zstd"
Traceback (most recent call last):
  File "<string>", line 1, in <module>
    from compression import zstd
  File "/var/lang/lib/python3.14/compression/zstd/__init__.py", line 29, in <module>
    import _zstd
ModuleNotFoundError: No module named '_zstd'

Is it a bug or is it intentional and we have to rebuild our own Python image if we want to use this new feature?

[charliermarsh]

We're also looking to use this.

[Etienne-gh]

@charliermarsh from AWS support:

The fix for this issue has been completed and will be deployed in the near future. This will ensure that the _zstd module is properly available in the Python 3.14 Lambda runtime, allowing you to use zstd compression functionality without encountering the ModuleNotFoundError.