Based on your error and the versions you're using, I can identify the likely cause: There's an incompatibility between Prefect 2.20.2 and Pydantic 2.8.2. Prefect 2.x series was designed to work with Pydantic 1.x, and using Pydantic 2.x can cause various typing-related issues, including the "TypeError: 'type' object is not iterable" error you're seeing. To resolve this, you have two options: 1. Recommended Solution: Downgrade Pydantic to version 1.x

bash
pip install "pydantic<2.0"

2. Alternative Solution: Upgrade to Prefect 3.x, which is fully compatible with Pydantic 2.x

bash
pip install -U "prefect>=3.0"

For your current setup (Prefect 2.20.2), the first option (downgrading Pydantic) is the most straightforward fix. Prefect 2.x was built and tested with Pydantic 1.x, and while it might work with some Pydantic 2.x features, it's not guaranteed to be fully compatible. To prevent similar issues in the future, you might want to consider: 1. Using a requirements.txt or poetry/pipenv to pin your dependencies 2. Upgrading to Prefect 3.x, which has been designed to work with newer versions of Pydantic Would you like me to provide more specific guidance about upgrading to Prefect 3.x, or would you prefer details about pinning your dependencies in Prefect 2.x?

I see what's happening now. You're absolutely right - this is a very recent issue that just emerged with Pydantic 2.11.4, which was released yesterday. The error you're seeing is a compatibility issue between Prefect 2.x and the latest Pydantic release. Here are your options, from least to most disruptive: 1. Pin Pydantic to version 2.11.3 or earlier

bash
   pip install "pydantic<2.11.4"

This is the easiest solution and should work with your other packages that require Pydantic 2.x. 2. Upgrade to Prefect 3.x (only if option 1 doesn't work for you)

bash
   pip install -U "prefect>=3.0"

I apologize for my earlier response suggesting downgrading to Pydantic 1.x - that was overly cautious advice. You're correct that Prefect 2.x has been working with Pydantic 2.x, and the issue you're experiencing is specifically related to the very latest Pydantic release (2.11.4). Try the first option of pinning Pydantic to 2.11.3 - this should resolve the error while maintaining compatibility with your other packages that require Pydantic 2.x.