ImportError: cannot import name 'mock_s3' from 'moto'

TL;DR: moto 5 deleted the per-service decorators like mocks3. Replace `from moto import mocks3 with from moto import mockaws`, and swap the @mocks3 decorator for @mock_aws.

ImportError: cannot import name 'mock_s3' from 'moto'

Fix it

1. Change the import: from moto import mock_aws. Expected: imports cleanly.
2. Change decorators: @mockaws instead of @mocks3 (it mocks all services). Expected: tests pass.
3. If you must stay on old decorators short-term: pip install "moto<5". Expected: mock_s3 works again, but you miss fixes.
4. Grep for other removed decorators in the same suite: mockdynamodb, mocksqs, etc. all became mock_aws. Expected: none left.

When this applies

• The import of mocks3 (or mockdynamodb, mock_sqs, ...) fails and moto is 5.x.

When it doesn't

• moto is 4.x: the old decorators exist; something else is wrong.
• The import works but mocks do nothing: check decorator placement and scope.

Compatibility

• moto >= 5.0. For 1.x-4.x, mock_s3 still exists.

Why it happens

moto unified dozens of per-service decorators into one mock_aws to simplify maintenance. The old names were removed, not deprecated, in 5.0.

Edge cases

• mock_aws mocks every service, which can surprise tests that relied on unmocked calls failing; scope tests accordingly.
• Server mode (moto_server) is unaffected by the decorator rename.

Reported in GitHub (gh:getmoto/moto#8498): ImportError: cannot import name 'mocks3' from 'moto' after v5 upgrade (getmoto/moto#8498). The verified fix: Asked on Stack Overflow by developers whose mocks3 import broke after upgrading moto. The verified answer: moto 5 replaced the per-service decorators with a single mockaws, so use from moto import mockaws instead. Source: the linked Stack Overflow thread. Source: https://github.com/getmoto/moto/issues/8498 Thread ref: gh:getmoto/moto#8498