modal setup: ImportError cannot import GRPCError from grpclib

TL;DR

For "ImportError: cannot import name 'GRPCError' from 'grpclib'": use a fresh virtual environment and a clean pip install modal, which pulls the pinned grpclib. python3 -m modal setup fails with: ` ImportError: cannot import name 'GRPCError' from 'grpclib' even after pip install --upgrade grpclib` reported 0.4.7.

ImportError: cannot import name 'GRPCError' from 'grpclib'

Steps

1. python3 -m modal setup fails with:

ImportError: cannot import name 'GRPCError' from 'grpclib'

2. even after pip install --upgrade grpclib reported 0.4.7.
3. The maintainer dug in and found the smoking gun: pip show grpclib in the

broken environment had an empty Summary and no PyPI metadata, meaning some other package had shadowed the real grpclib install. Upgrading cannot fix it because pip thinks the requirement is already satisfied.

4. Use a fresh virtual environment and a clean pip install modal, which pulls

the pinned grpclib. The reporter confirmed everything worked in a fresh virtualenv. Avoid installing modal into an old project environment where another package may have dropped a fake grpclib.

5. pip show grpclib: empty Summary and missing metadata is the tell for a

shadowed install. If you see that, stop upgrading and start a fresh env.

When to use

You are seeing this: The reporter confirmed everything worked in a fresh virtualenv. Use this skill when you run into "modal setup: ImportError cannot import GRPCError from grpclib".

When not to use

If your error message or symptom does not match what is described above, this is probably not your fix. Search for your exact error text instead of forcing this one to fit.

Versions

Versions mentioned in the source: reported 0.4.7. If you are on something much newer or older, the details may have shifted.

Why this happens

Upgrading cannot fix it because pip thinks the requirement is already satisfied.

A user asked why python3 -m modal setup failed with ImportError: cannot import name GRPCError from grpclib even after pip install --upgrade grpclib reported 0.4.7. The verified resolution from the maintainer: pip show grpclib in the broken environment had an empty Summary and no PyPI metadata, meaning another package shadowed the real grpclib install; the reliable fix is a fresh virtual environment with a clean pip install modal, confirmed by the reporter. Thread: https://vectle.com/threads/thr_j5oFPHzwbFzk7s7K2aD7pA