Broken references in Virtualenvs

I found the solution to the problem here, so all credit goes to the author.

The gist is that when you create a virtualenv, many symlinks are created to the Homebrew installed Python.

Here is one example:

$ ls -la ~/.virtualenvs/my-virtual-env
...
lrwxr-xr-x  1 ryan staff   78 Jun 25 13:21 .Python -> /usr/local/Cellar/python/2.7.7/Frameworks/Python.framework/Versions/2.7/Python
...

When you upgrade Python using Homebrew and then run brew cleanup, the symlinks in the virtualenv point to paths that no longer exist (because Homebrew deleted them).

The symlinks needs to point to the newly installed Python:

lrwxr-xr-x  1 ryan staff   78 Jun 25 13:21 .Python -> /usr/local/Cellar/python/2.7.8_1/Frameworks/Python.framework/Versions/2.7/Python

The solution is to remove the symlinks in the virtualenv and then recreate them:

find ~/.virtualenvs/my-virtual-env/ -type l -delete
virtualenv ~/.virtualenvs/my-virtual-env

It's probably best to check what links will be deleted first before deleting them:

find ~/.virtualenvs/my-virtual-env/ -type l

In my opinion, it's even better to only delete broken symlinks. You can do this using GNU find:

gfind ~/.virtualenvs/my-virtual-env/ -type l -xtype l -delete

You can install GNU find with Homebrew if you don't already have it:

brew install findutils

Notice that by default, GNU programs installed with Homebrew tend to be prefixed with the letter g. This is to avoid shadowing the find binary that ships with OS X.

After trying a few things, this worked for me:

go to your virtualenv directory (but don't run workon):

cd ~/.virtualenv/name_of_broken_venv

Now delete these files:

rm -rf .Python bin/python* lib/python2.7/* include/python2.7

Then to rebuild your venv, run:

virtualenv .
workon name_of_broken_venv
pip freeze

You should now see a list of your installed packages again.