Flask_sqlalchemy: Error With `__setattr__` To `DefaultMeta`

After re-building a Docker image, I've started to get the following error: $ docker run --rm -it python:3.8-slim /bin/bash ... $ pip install flask_sqlalchemy ... $ python -c 'from

Solution 1:

After some experimentation, it seems like the issue is due to some change between python:3.8.3-slim and python:3.8.4-slim.

To reproduce, notice that this works:

$ docker run --rm -it python:3.8.3-slim …

Where this does not:

docker run --rm -it python:3.8.4-slim …

It looks like this bug/fix is the cause of the issue: https://bugs.python.org/issue39960