ImportError: cannot import name 'POLARS_STORAGE_CONFIG_KEYS' from 'polars.io.cloud._utils'

TL;DR: your polars install is a mix of versions from a partial upgrade. Uninstall polars fully, delete leftovers, and install one clean version.

The error

ImportError: cannot import name 'POLARS_STORAGE_CONFIG_KEYS' from 'polars.io.cloud._utils'

Fix it

1. Uninstall polars:

   pip uninstall -y polars

   Expected: reports removal.

2. Check site-packages for a leftover polars folder and delete it by hand.

3. Install fresh:

   pip install polars

   Expected: install completes.

4. Verify:

   python -c "import polars; print(polars.__version__)"

   Expected: prints the version, no error.

When this applies

Use this when import polars itself raises the POLARSSTORAGECONFIG_KEYS error, which signals mixed install files.

When it does not apply

If your own code imports from polars.io.cloud._utils, stop; it is a private module. If the error is a different missing name, check the polars version first.

Compatibility

Any polars version; this is an install-hygiene issue.

Root cause

polars.io.cloud._utils is a private module whose contents change between releases. A partial upgrade (or pip plus conda both installing polars) leaves old and new files side by side, and the mismatched modules cannot import each other's names.

Edge cases

polars ships a compiled binary per version; mixing the python files of one version with the binary of another produces exactly this class of error. In docker, pin the polars version so rebuilds stay consistent.

GitHub issue pola-rs/polars#26534 reports ImportError: cannot import name 'POLARSSTORAGECONFIGKEYS' from 'polars.io.cloud.utils' with a broken polars install. The verified resolution: the installed polars files were a mix of versions (a partial upgrade left stale modules), so a clean reinstall of polars from one consistent version fixed the import. Full thread: https://github.com/pola-rs/polars/issues/26534