BUG: Cannot sort by columns named None

[zvun]

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Reproducible Example

import pandas as pd

df = pd.DataFrame([[1, 2], [3, 4]], columns=['C1', None])
df.sort_values(None) # KeyError: None

Issue Description

Sorting a DataFrame by a column named None results in the error KeyError: None. This breaks e.g. plugins that depend on Pandas for viewing and sorting DataFrames (see a related DataWrangler issue here, where inconsistent behavior with columns named None has also been reported).

Expected Behavior

A column named None should not result in inconsistent behavior where some operations work but some others don't.

Installed Versions

INSTALLED VERSIONS

commit : 0691c5c
python : 3.11.2
python-bits : 64
OS : Linux
OS-release : 6.1.0-32-amd64
Version : #1 SMP PREEMPT_DYNAMIC Debian 6.1.129-1 (2025-03-06)
machine : x86_64
processor :
byteorder : little
LC_ALL : None
LANG : None
LOCALE : en_US.UTF-8

pandas : 2.2.3
numpy : 2.2.6
pytz : 2025.2
dateutil : 2.9.0.post0
pip : 25.0
Cython : None
sphinx : None
IPython : 9.2.0
adbc-driver-postgresql: None
adbc-driver-sqlite : None
bs4 : None
blosc : None
bottleneck : None
dataframe-api-compat : None
fastparquet : None
fsspec : None
html5lib : None
hypothesis : None
gcsfs : None
jinja2 : None
lxml.etree : None
matplotlib : 3.10.3
numba : None
numexpr : None
odfpy : None
openpyxl : None
pandas_gbq : None
psycopg2 : None
pymysql : None
pyarrow : None
pyreadstat : None
pytest : 8.3.5
python-calamine : None
pyxlsb : None
s3fs : None
scipy : None
sqlalchemy : None
tables : None
tabulate : None
xarray : None
xlrd : None
xlsxwriter : None
zstandard : None
tzdata : 2025.2
qtpy : None
pyqt5 : None