Noisy pydantic warning when using cfn-lint

[qmg-tmay]

CloudFormation Lint Version

1.40.3

What operating system are you using?

Mac

Describe the bug

When running cfn-lint installed via brew, I receive the following warning:

/opt/homebrew/Cellar/cfn-lint/1.40.3/libexec/lib/python3.14/site-packages/samtranslator/compat.py:2: UserWarning: Core Pydantic V1 functionality isn't compatible with Python 3.14 or greater.

Lint results are still returned.

Expected behavior

Warning should not appear

Reproduction template

Warning occurs when running any cfn-lint command e.g. cfn-lint --version

[kddejong]

#4266 and aws/serverless-application-model#3831. Keeping this open for tracking.

[StevenStreib]

I'm also experiencing this, and it has a nasty little side effect when using the extension for VS Code, a persistent warning message on any open CloudFormation or SAM template:

[dciszewski]

Try brew reinstall pydantic

[kimmoahokas]

brew just changed their packaged cfn-lint to use python 3.13. Run brew update && brew reinstall cfn-lint to fix the warning.
Homebrew/homebrew-core#255031

Would be also great if #4266 was merged so it's more clear python 3.14 is not supported yet.

[krokofant]

brew just changed their packaged cfn-lint to use python 3.13. Run brew update && brew reinstall cfn-lint to fix the warning. Homebrew/homebrew-core#255031

Would be also great if #4266 was merged so it's more clear python 3.14 is not supported yet.

Didn't work for me yesterday, perhaps some staged rollout? Tried to restart vscode as well but no luck.

[davidjb]

This issue is raising a RuntimeError for me with Python 3.14 and cfn-lint v1.43.3:

RuntimeError: no validator found for <class 'pydantic.v1.fields.UndefinedType'>, see arbitrary_types_allowed in Config

The issue is because cfn-lint is using the samtranslator Python package. The issue is known about upstream in aws/serverless-application-model#3831 and being worked on aws/serverless-application-model#3862 to upgrade to Pydantic 2.