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• I have confirmed this bug exists on the latest version of pandas.

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Code Sample

import pandas as pd import numpy as np a = pd.DataFrame({'a': ['a', 'b', 'c'], 'b': ['d', '', '']}, dtype='object') b = pd.DataFrame({'a': ['a', 'b', 'c'], 'b': ['d', '', '']}, dtype='string') print(a) a.replace(r'^\s*$', pd.NA, regex=True, inplace=True) print(a) print(b) b.replace(r'^\s*$', pd.NA, regex=True, inplace=True) print(b)

Problem description

replace(r'^\s*$', pd.NA, regex=True, inplace=True) works on object dtype, but not on stringdtype

Expected Output

Same on both replacement

Output of pd.show_versions()