●Change8

Migrating to Polars py-1.42.0

Version py-1.42.0 introduces 1 breaking change. This guide details how to update your code.

Released: 6/24/2026

1
Breaking Changes
1
Migration Steps
8
Affected Symbols

⚠️ Check Your Code

If you use any of these symbols, you need to read this guide:

Expr.is_sortedDataFrame.is_sorted()dt.truncatedt.round.explode()scan_icebergsink_* functionsHConcat

Breaking Changes

●Issue #1

Deprecate casts from string to temporal dtypes. This may break code relying on implicit string-to-datetime/date/time conversions.

Migration Steps

  1. 1
    If you relied on implicit string-to-temporal casting, update your code to explicitly cast strings to temporal types.

Release Summary

This release introduces performance improvements across cloud IO and expression evaluation, adds experimental features like out-of-core spilling and strict mode, and fixes numerous bugs related to SQL, projection pushdown, and joins. Notably, it deprecates implicit string-to-temporal casts.

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View the full release notes and all changes for Polars py-1.42.0.

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