运行 jupyter 会产生“ModuleNotFoundError: No module named 'six'”

Question

I've just upgraded to OSX 11.0.1. Now when I try to run a jupyter notebook I'm getting this error:

% jupyter notebook
Traceback (most recent call last):
  File "/usr/local/bin/jupyter-notebook", line 5, in <module>
    from notebook.notebookapp import main
  File "/usr/local/lib/python3.8/site-packages/notebook/notebookapp.py", line 83, in <module>
    from .services.kernels.kernelmanager import MappingKernelManager, AsyncMappingKernelManager
  File "/usr/local/lib/python3.8/site-packages/notebook/services/kernels/kernelmanager.py", line 18, in <module>
    from jupyter_client.session import Session
  File "/usr/local/lib/python3.8/site-packages/jupyter_client/session.py", line 41, in <module>
    from jupyter_client.jsonutil import extract_dates, squash_dates, date_default
  File "/usr/local/lib/python3.8/site-packages/jupyter_client/jsonutil.py", line 10, in <module>
    from dateutil.parser import parse as _dateutil_parse
  File "/usr/local/lib/python3.8/site-packages/dateutil/parser/__init__.py", line 2, in <module>
    from ._parser import parse, parser, parserinfo, ParserError
  File "/usr/local/lib/python3.8/site-packages/dateutil/parser/_parser.py", line 42, in <module>
    import six
ModuleNotFoundError: No module named 'six'

If I do pip install six I see:

Requirement already satisfied: six in 
   /usr/local/Cellar/protobuf/3.13.0_1/libexec/lib/python3.9/site-packages (1.15.0)

I'm quite confused by this as (a) I don't know what this path is and (b) it doesn't seem to be in my PATH or PYTHONPATH , so I don't know why pip is looking for it there.

What should I do?

For reference: I think I installed jupyter via pip originally I don't know how I installed jupyter, and I'm not using anaconda (and would prefer to continue not to do so). Other info in case useful:

% type jupyter
jupyter is /usr/local/bin/jupyter
% type python 
python is an alias for /usr/local/bin/python3
% ls -al /usr/local/bin/python3
lrwxr-xr-x  1 me  admin  40 12 Nov 23:12 /usr/local/bin/python3 -> ../Cellar/python@3.9/3.9.0_1/bin/python3

Update: if I do pip list -v then I can see that most packages are where I'd expect them to be, with the exception of protobuf and six. I wonder why they are in a different location?

% pip list -v
Package                 Version   Location                                                                Installer
----------------------- --------- ----------------------------------------------------------------------- ---------
appdirs                 1.4.4     /usr/local/lib/python3.9/site-packages                                  pip
asgiref                 3.3.1     /usr/local/lib/python3.9/site-packages                                  pip
...
protobuf                3.13.0    /usr/local/Cellar/protobuf/3.13.0_1/libexec/lib/python3.9/site-packages
...
six                     1.15.0    /usr/local/Cellar/protobuf/3.13.0_1/libexec/lib/python3.9/site-packages

Answer 1

I just ran into the same error (in OS 11.1 and py3.8).

And running pip install --ignore-installed six did the trick for me.