An error is thrown when running a flow with PyTorch imported:

Traceback (most recent call last):
  File ".../site-packages/metaflow/cli.py", line 649, in main
    start(auto_envvar_prefix="METAFLOW", obj=state)
  ...
  File ".../site-packages/metaflow/package/__init__.py", line 87, in __init__
    self._mfcontent = MetaflowCodeContentV1(criteria=_module_selector)
  File ".../site-packages/metaflow/packaging_sys/v1.py", line 64, in __init__
    self._modules = {
  File ".../site-packages/metaflow/packaging_sys/v1.py", line 67, in <dictcomp>
    set(
TypeError: '_ClassNamespace' object is not iterable

To reproduce, try the helloworld.py example with import torch at the top (using the latest versions torch==2.7.1 and metaflow==2.16.5).

PyTorch adds a custom ModuleType-derived class to sys.modules here, which defines __getattr__ to always return a _ClassNamespace object. Unfortunately, that means that getattr(<that module>, "__path__") returns something unexpected.

IMO PyTorch is at fault here, but PyTorch has had this code for a while (maybe 11 months) so it's likely that many Metaflow users cannot use the most recent versions with PyTorch.