Thanks for the heads up. A couple quick clarifying questions so I can give you a precise fix: - What Prefect version are you running (

prefect version

output)? - What’s the exact error message/traceback? - Are you running an “agent” (Prefect 2.x) or a “worker” (Prefect 3.x), and in what environment (local, Docker image, Kubernetes)? - What versions of

pydantic

and

pydantic-settings

are installed? Why I’m asking: Pydantic v2 is only compatible with Prefect 3.x. Prefect 2.x relied on Pydantic v1 APIs, so upgrading just Pydantic to v2 on a Prefect 2.x agent will break with import/validator errors. Two common situations and fixes: 1) You’re on Prefect 2.x (agents) - Symptom: ImportError/TypeError due to Pydantic v2 (e.g.,

cannot import name BaseSettings

, validator errors). - Fix: Pin Pydantic to v1 and avoid v2.

pip install "prefect<3" "pydantic<2"

- Longer-term: consider upgrading to Prefect 3.x workers to use Pydantic v2. 2) You’re on Prefect 3.x (workers) and just updated dependencies - There is a known breaking change in

pydantic-settings

2.9.0 that causes: ImportError: cannot import name 'ConfigFileSourceMixin' from 'pydantic_settings.sources' - Temporary fix: pin

pydantic-settings

to 2.8.1 (or any version < 2.9.0 until a Prefect fix is released).

pip install "pydantic>=2,<3" "pydantic-settings>=2,<2.9.0"

- Details: Issue: pydantic-settings 2.9.0 breaking change - Background on 2.x vs 3.x and Pydantic v2 adoption: Support installation with Pydantic v2 If you paste the exact error and your

prefect version

plus the

pip freeze

lines for `pydantic`/`pydantic-settings`, I can confirm which path you’re on and give a targeted set of commands (and if you’re using a Docker/Helm image, I can suggest the right base image/pins).