Python 3.10+

AttributeError: module 'collections' has no attribute 'Mapping'

AttributeError: module 'collections' has no attribute 'Mapping'

What it means

The abstract base classes moved from collections to collections.abc; the old aliases were removed in Python 3.10.

Why it happens

collections.Mapping (and Sequence, Iterable, etc.) were deprecated aliases since Python 3.3 and removed in 3.10. Older code or a stale dependency still references collections.Mapping.

How to fix it

1. Import from collections.abc: `from collections.abc import Mapping`.
2. Replace references like `collections.Mapping` with `collections.abc.Mapping`.
3. Upgrade dependencies that still use the old path (a common offender in older pyyaml/jsonschema pins).

Related deadline: Lambda Python 3.9 EOL — 2027-02-01.

Find every instance in your project

The free EOLkits scanner runs in your browser (nothing uploaded) and flags this and related breakages across your IaC and dependency files.

Primary source: https://docs.python.org/3/whatsnew/3.10.html

Get the full migration audit — $299, hash-anchored PDF →