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.