What's new in 2.1.2 (October ??, 2023)

These are the changes in pandas 2.1.2. See :ref:`release` for a full changelog including other versions of pandas.

Fixed regressions

Fixed bug where PDEP-6 warning about setting an item of an incompatible dtype was being shown when creating a new conditional column (:issue:`55025`)
Fixed regression in :meth:`DataFrame.join` where result has missing values and dtype is arrow backed string (:issue:`55348`)
Fixed regression in :meth:`DataFrame.resample` which was extrapolating back to origin when origin was outside its bounds (:issue:`55064`)
Fixed regression in :meth:`DataFrame.sort_index` which was not sorting correctly when the index was a sliced :class:`MultiIndex` (:issue:`55379`)
Fixed performance regression with wide DataFrames, typically involving methods where all columns were accessed individually (:issue:`55256`, :issue:`55245`)

Fixed bug in :meth:`Categorical.equals` if other has arrow backed string dtype (:issue:`55364`)
Fixed bug in :meth:`DataFrame.__setitem__` not inferring string dtype for zero-dimensional array with infer_string=True (:issue:`55366`)
Fixed bug in :meth:`DataFrame.idxmin` and :meth:`DataFrame.idxmax` raising for arrow dtypes (:issue:`55368`)
Fixed bug in :meth:`DataFrame.interpolate` raising incorrect error message (:issue:`55347`)
Fixed bug in :meth:`Index.insert` raising when inserting None into :class:`Index` with dtype="string[pyarrow_numpy]" (:issue:`55365`)
Fixed bug in :meth:`Series.all` and :meth:`Series.any` not treating missing values correctly for dtype="string[pyarrow_numpy]" (:issue:`55367`)
Fixed bug in :meth:`Series.floordiv` for :class:`ArrowDtype` (:issue:`55561`)
Fixed bug in :meth:`Series.rank` for string[pyarrow_numpy] dtype (:issue:`55362`)
Fixed bug in :meth:`Series.str.extractall` for :class:`ArrowDtype` dtype being converted to object (:issue:`53846`)
Silence Period[B] warnings introduced by :issue:`53446` during normal plotting activity (:issue:`55138`)

Fixed non-working installation of optional dependency group output_formatting. Replacing underscore _ with a dash - fixes broken dependency resolution. A correct way to use now is pip install pandas[output-formatting].