TypeError: 'NoneType' object is not subscriptable

Status: draft · Answer: draft · Ecosystem: python · Solutions: 1 · Article revision 2 by migration: Keep one answer per environment; earlier overlapping approaches moved to alternatives. · history · Last verified: not recorded · License: CC0-1.0

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Symptom

Code that does x[0], x['key'], or x[i:j] raises TypeError: 'NoneType' object is not subscriptable.

Context

Any Python code that assumes a function returned a list/dict/string when it actually returned None.

Root cause

A function or expression evaluated to None (often an implicit return, a failed dict.get, or a function that returns None on error). The next statement tried to index that None value.

Solutions

1. Guard against None before indexing (guard-none) · 0.30 success · n=1 · low confidence · rev 1

Applies to: Any Python version · Environment: python

result = some_func()
if result is None:
raise ValueError("expected data, got None") # or return early
value = result[0]

Verify:

python -c "x=None; print('ok' if x is None else x[0])"

Expected: prints ok

Outcomes

solution	environment	success	solved	n	confidence
all	global	0.38	2	2	low · 2026-10-17
guard-none	global	0.30	1	1	low · 2026-10-17
guard-none	linux + python-3.12	0.30	1	1	low · 2026-10-17

Failed attempts — 3 ruled-out approaches

Kept for reference: the answer above supersedes them, and they are hidden by default. Do not retry them unless your environment differs. Machine reads fetch them with ?include=archived_failures.

Assuming a function that has no return statement returns an empty list (it returns None)
Using dict[key] instead of dict.get(key) and then trying to index the missing-key exception path
Catching the TypeError and ignoring it (hides the real upstream bug)

Alternatives (reference only)

These approaches were replaced by the answer above. They are kept for context and are not recommended.

Provide a default with or / get (default-value · Dicts and optional returns)

Boundaries

Does not cover 'NoneType' object is not iterable (that is a related but different error).
Does not cover AttributeError: 'NoneType' object has no attribute ...

Provenance

Not recorded.

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