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# What’s new in 1.1.5 (December 07, 2020)

These are the changes in pandas 1.1.5. See Release notes for a full changelog including other versions of pandas.

## Fixed regressions

- Fixed regression in addition of a timedelta-like scalar to a `DatetimeIndex` raising incorrectly (GH 37295)

- Fixed regression in `Series.groupby()` raising when the `Index` of the `Series` had a tuple as its name (GH 37755)

- Fixed regression in `DataFrame.loc()` and `Series.loc()` for `__setitem__` when one-dimensional tuple was given to select from `MultiIndex` (GH 37711)

- Fixed regression in inplace operations on `Series` with `ExtensionDtype` with NumPy dtyped operand (GH 37910)

- Fixed regression in metadata propagation for `groupby` iterator (GH 37343)

- Fixed regression in `MultiIndex` constructed from a `DatetimeIndex` not retaining frequency (GH 35563)

- Fixed regression in `Index` constructor raising a `AttributeError` when passed a `SparseArray` with datetime64 values (GH 35843)

- Fixed regression in `DataFrame.unstack()` with columns with integer dtype (GH 37115)

- Fixed regression in indexing on a `Series` with `CategoricalDtype` after unpickling (GH 37631)

- Fixed regression in `DataFrame.groupby()` aggregation with out-of-bounds datetime objects in an object-dtype column (GH 36003)

- Fixed regression in `df.groupby(..).rolling(..)` with the resulting `MultiIndex` when grouping by a label that is in the index (GH 37641)

- Fixed regression in `DataFrame.fillna()` not filling `NaN` after other operations such as `DataFrame.pivot()` (GH 36495).

- Fixed performance regression in `df.groupby(..).rolling(..)` (GH 38038)

- Fixed regression in `MultiIndex.intersection()` returning duplicates when at least one of the indexes had duplicates (GH 36915)

- Fixed regression in `DataFrameGroupBy.first()`, `SeriesGroupBy.first()`, `DataFrameGroupBy.last()`, and `SeriesGroupBy.last()` where `None` was considered a non-NA value (GH 38286)

## Bug fixes

- Bug in pytables methods in python 3.9 (GH 38041)

## Other

- Only set `-Werror` as a compiler flag in the CI jobs (GH 33315, GH 33314)

## Contributors

A total of 12 people contributed patches to this release. People with a “+” by their names contributed a patch for the first time.

- Andrew Wieteska

- Fangchen Li

- Janus

- Joris Van den Bossche

- Matthew Roeschke

- MeeseeksMachine

- Pandas Development Team

- Richard Shadrach

- Simon Hawkins

- Uwe L. Korn

- jbrockmendel

- patrick