Pip Fails With AttributeError: 'module' Object Has No Attribute '_init_cffi_1_0_external_module'

I recently found that pip was completely broken for me. This is on Ubuntu bionic 18.04. $ pip --version Traceback (most recent call last):

Solution 1:

After looking at this some more, I discovered that the Fedora bug report above had information that really helped:

at some point, cffi 1.1.2 from pip is being overwritten with cffi 0.8.6 from the python-cffi package. As cryptography 1.1.2 is making a call to the cffi_1_0_external_module' it doesn't exists and thus fails.

I dug around, and found that I had an obsolete cffi version in ~/.local/lib/python2.7/site-packages/ (presumably from a pip install --user ... some years ago).

A general way to explore that and check versions is:

>>> import cffi
>>> cffi.__version__
'0.8.6'
>>> cffi
<module 'cffi' from '$HOME/.local/lib/python2.7/site-packages/cffi/__init__.pyc'>

Removing that directory fixed pip, but presumably could have interefered with something else I installed long ago.

I also hear that it can help in some related situations to use easy_install (since pip isn't working...) to upgrade cffi:

easy_install -U cffi

I'm still curious if there is a large lesson here about how to avoid this sort of thing in the future.

• Why is cffi both within pip and an external package?
• Are local installs dangerous, since they persist past OS and Python upgrades?
• Are there general packaging/dependency best practices that would avoid these sorts of package dependency problems?