BUG: Index.get_level_values() does not handle boolean, pd.NA, np.nan, or pd.NaT `level` correctly

[sfc-gh-mvashishtha]

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Reproducible Example

import pandas as pd
pd.Index([], name=True).get_level_values(level=True)

Issue Description

I get IndexError: Too many levels: Index has only 1 level, not 2. Also, pd.Index([], name=True).get_level_values(level=False) should raise KeyError, but it returns the whole index.

Also, name np.nan, pd.NA or pd.NaT causes KeyError: 'Requested level (nan) does not match index name (nan)'.

Expected Behavior

I should get the whole index from get_level_values(True)

Installed Versions

---

commit : 4665c10
python : 3.13.5
python-bits : 64
OS : Darwin
OS-release : 24.6.0
Version : Darwin Kernel Version 24.6.0: Mon Jul 14 11:30:30 PDT 2025; root:xnu-11417.140.69~1/RELEASE_ARM64_T6020
machine : arm64
processor : arm
byteorder : little
LC_ALL : None
LANG : en_US.UTF-8
LOCALE : en_US.UTF-8

pandas : 2.3.2
numpy : 2.3.2
pytz : 2025.2
dateutil : 2.9.0.post0
pip : 25.1
Cython : None
sphinx : None
IPython : 9.4.0
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 : None
numba : None
numexpr : None
odfpy : None
openpyxl : None
pandas_gbq : None
psycopg2 : None
pymysql : None
pyarrow : None
pyreadstat : None
pytest : None
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

[Alvaro-Kothe]

The issue stems from the _validate_index_level function:

pandas/pandas/core/indexes/base.py

Lines 2000 to 2021 in 4665c10

	def _validate_index_level(self, level) -> None:
	"""
	Validate index level.
	For single-level Index getting level number is a no-op, but some
	verification must be done like in MultiIndex.
	"""
	if isinstance(level, int):
	if level < 0 and level != -1:
	raise IndexError(
	"Too many levels: Index has only 1 level, "
	f"{level} is not a valid level number"
	)
	if level > 0:
	raise IndexError(
	f"Too many levels: Index has only 1 level, not {level + 1}"
	)
	elif level != self.name:
	raise KeyError(
	f"Requested level ({level}) does not match index name ({self.name})"
	)

The problem arises because isinstance(False, int) and isinstance(True, int) both return True. Additionally, the inequality check evaluates to True for np.nan and pd.NaT, though I expected a distinct error for pd.NA.

Anyway, since get_level_values is essentially a no-op for Index, addressing edge cases for non-string names doesn’t seem worth the effort.

[whyvineet]

@Alvaro-Kothe can you review my PR?

[rhshadrach]

@vam5h1 - it appears you are using AI to generate comments on various issuse (#62097, #62050). Please do not do this, we consider this spam.