[SOLVED] pip cannot uninstall <package>: "It is a distutils installed project"

pip cannot uninstall <package>: "It is a distutils installed project"

I tried to install the Twilio module:

sudo -H pip install twilio

And I got this error:

Installing collected packages: pyOpenSSL
  Found existing installation: pyOpenSSL 0.13.1
Cannot uninstall 'pyOpenSSL'. It is a distutils installed project and             
thus we cannot accurately determine which files belong to it which 
would lead to only a partial uninstall.

Anyone know how to uninstall pyOpenSSL?

Solution

This error means that this package's metadata doesn't include a list of files that belong to it. Most probably, you have installed this package via your OS' package manager, so you need to use that rather than pip to update or remove it, too.

See e.g. Upgrading to pip 10: It is a distutils installed project and thus we cannot accurately determine which files belong to it which would lead to only a partial uninstall. · Issue #5247 · pypa/pip for one such example where the package was installed with apt.

Alternatively, depending on your needs, it may be more productive to not use your system Python and/or its global environment but create a private Python installation and/or environment. There are many options here including virtualenv, venv, pyenv, pipenv and installing Python from source into /usr/local or $HOME/$HOME/.local (or /opt/<whatever>).

Finally, I must comment on the often-suggested (e.g. at pip 10 and apt: how to avoid "Cannot uninstall X" errors for distutils packages) --ignore-installed pip switch.

It may work (potentially for a long enough time for your business needs), but may just as well break things on the system in unpredictable ways. One thing is sure: it makes the system's configuration unsupported and thus unmaintainable -- because you have essentially overwritten files from your distribution with some other arbitrary stuff. E.g.:

If the new files are binary incompatible with the old ones, other software from the distribution built to link against the originals will segfault or otherwise malfunction.
If the new version has a different set of files, you'll end up with a mix of old and new files which may break dependent software as well as the package itself.
If you change the package with your OS' package manager later, it will overwrite pip-installed files, with similarly unpredictable results.
If there are things like configuration files, differences in them between the versions can also lead to all sorts of breakage.