Just an update on this. We downgraded the docker image to python 3.8 and it fixed the issue. We may want tell people that lamdex is incompatible with python 3.9.

hm, yea: i’m not sure if that is known. would you mind filing an issue against github.com/pantsbuild/lambdex/ ?

Lambdex definitely works with Python 3.9. I have provided Lambdex support to several users in the past few months where I actually went through the exercise out on AWS. This is something else.