What’s new in 1.2.3 (March 02, 2021)

These are the changes in pandas 1.2.3. See Release notes for a full changelog including other versions of pandas.

Fixed regressions

  • Fixed regression in to_excel() raising KeyError when giving duplicate columns with columns attribute (GH39695)

  • Fixed regression in nullable integer unary ops propagating mask on assignment (GH39943)

  • Fixed regression in DataFrame.__setitem__() not aligning DataFrame on right-hand side for boolean indexer (GH39931)

  • Fixed regression in to_json() failing to use compression with URL-like paths that are internally opened in binary mode or with user-provided file objects that are opened in binary mode (GH39985)

  • Fixed regression in Series.sort_index() and DataFrame.sort_index(), which exited with an ungraceful error when having kwarg ascending=None passed. Passing ascending=None is still considered invalid, and the improved error message suggests a proper usage (ascending must be a boolean or a list-like of boolean) (GH39434)

  • Fixed regression in DataFrame.transform() and Series.transform() giving incorrect column labels when passed a dictionary with a mix of list and non-list values (GH40018)


A total of 14 people contributed patches to this release. People with a “+” by their names contributed a patch for the first time.

  • Daniel Saxton

  • Dylan Percy +

  • Jody Klymak +

  • Maxim Ivanov

  • MeeseeksMachine

  • Pandas Development Team

  • Richard Shadrach

  • Rohit Gupta +

  • Simon Hawkins

  • Torsten Wörtwein

  • jbrockmendel

  • morrme +

  • partev

  • patrick