# Cache issues with Python virtualenvs

**URL:** <https://discuss.circleci.com/t/cache-issues-with-python-virtualenvs/2676>\
**Category:** Bug Reports\
**Tags:** python\
**Created:** [March 14, 2016, 11:10am UTC](https://discuss.circleci.com/t/cache-issues-with-python-virtualenvs/2676 "2016-03-14T11:10:41Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![rutsky](https://avatars.discourse-cdn.com/v4/letter/r/ecb155/32.png) [@rutsky](https://discuss.circleci.com/u/rutsky)\
**Post date:** [March 14, 2016, 11:10am UTC](https://discuss.circleci.com/t/cache-issues-with-python-virtualenvs/2676/1 "2016-03-14T11:10:41Z")

</div>

I’m trying to use Circle CI to test Buildbot project.

From time to time following issue occurs during installation of python packages:

```
$ pip install -e pkg -e master -e slave -e worker

Traceback (most recent call last):
  File "/home/ubuntu/virtualenvs/venv-2.7.11/bin/pip", line 7, in <module>
    from pip import main
  File "/home/ubuntu/virtualenvs/venv-2.7.11/lib/python2.7/site-packages/pip/ __init__.py", line 4, in <module>
    import logging
  File "/home/ubuntu/.pyenv/versions/2.7.11/lib/python2.7/logging/ __init__.py", line 26, in <module>
    import sys, os, time, cStringIO, traceback, warnings, weakref, collections
  File "/home/ubuntu/.pyenv/versions/2.7.11/lib/python2.7/collections.py", line 9, in <module>
    from operator import itemgetter as _itemgetter, eq as _eq

pip install -e pkg -e master -e slave -e worker returned exit code 1

ImportError: /home/ubuntu/virtualenvs/venv-2.7.11/lib/python2.7/lib-dynload/operator.so: undefined symbol: _PyUnicodeUCS4_AsDefaultEncodedString Action failed: pip install -e pkg -e master -e slave -e worker

```

For example here: [https://circleci.com/gh/buildbot/buildbot/112](https://circleci.com/gh/buildbot/buildbot/112)

This issue is not correlating with author of PR, is this PR or project branch, or with changed code (this error occurs before any actual project testing is started).

I debugged this issue [here](https://github.com/buildbot/buildbot/pull/2034) and my conclusion was following: sometimes Circle CI uses cached virtualenv directory that is incompatible with Python environment on used Circle CI VM.

Restarting build without cache usually “fixes” specific build (failed: [circleci.com/gh/buildbot/buildbot/77](http://circleci.com/gh/buildbot/buildbot/77)), fixed: [circleci.com/gh/buildbot/buildbot/78](http://circleci.com/gh/buildbot/buildbot/78)).

Here is circle.yml that I use:

```
machine:
  python:
    version: 2.7.11

dependencies:
  override:
    - pyenv global 2.7.11
    - pip install -e pkg -e master -e slave

test:
  override:
    - make docs

general:
  artifacts:
    - "master/docs/_build/html/"

```

Notice, that it’s not important what is being installed, since `pip` startup fails.

Is this is a Circle CI bug? (I think it is.)

Or is this my misconfiguration?

---

<div class="post-metadata">

**Author:** ![system](https://global.discourse-cdn.com/circleci/original/3X/5/1/511608acda8e85906e15909b57bd0a46c1dbe291.png) [@system](https://discuss.circleci.com/u/system)\
**Post date:** [June 18, 2018, 11:34am UTC](https://discuss.circleci.com/t/cache-issues-with-python-virtualenvs/2676/2 "2018-06-18T11:34:02Z")

</div>