AWS Lambda's python3.9, 3.10, and 3.11 runtimes are on the deprecation track; python3.12 (on Amazon Linux 2023) is the target. The runtime swap is one line — but Python 3.12 itself removed a pile of long-deprecated stdlib, so code that ran on 3.9 throws on import.
The removals you'll hit
ModuleNotFoundError: No module named 'distutils' — removed in 3.12 (PEP 632). Replace with setuptools + packaging (e.g. packaging.version.Version instead of distutils.version.LooseVersion). Interim: pip install 'setuptools<81' (still vendors a shim).
ModuleNotFoundError: No module named 'imp' — removed in 3.12. Use importlib (importlib.util.find_spec, import_module).
AttributeError: module 'collections' has no attribute 'Mapping' — the ABCs moved to collections.abc (removed from collections in 3.10). from collections.abc import Mapping.
DeprecationWarning: datetime.datetime.utcnow() is deprecated — use datetime.now(datetime.timezone.utc).
The one that isn't in your code
/lib64/libc.so.6: version `GLIBC_2.28' not found
Native wheels (cryptography, numpy, pydantic-core…) link against the glibc of the box that built them. AL2 runtimes ship glibc 2.26; AL2023 (python3.12) ships 2.34. Build for the target: pip install --platform manylinux2014_x86_64 --only-binary=:all: --target ./package <pkg>, or build inside public.ecr.aws/lambda/python:3.12. Match the arch (x86_64 vs arm64) too.
When AWS blocks you
The runtime parameter of python3.9 is no longer supported for creating or updating AWS Lambda functions
That's the block date. Set Runtime: python3.12 (SAM/CFN), lambda.Runtime.PYTHON_3_12 (CDK), or runtime = "python3.12" (Terraform), fix the imports above, redeploy.
The free EOLkits scanner flags every deprecated runtime and the dependency breaks above from your requirements.txt / pyproject.toml / IaC — in your browser, nothing uploaded. There's an MIT CLI (python-pivot) that codemods most of it, and a hash-anchored audit if you want it scored and done for you.
Cited deadlines + per-error fixes: eolkits.com/migrate · eolkits.com/fix
