Problem with virtualenv in Mac OS X

Question

I've installed virtualenv via pip and get this error after creating a new environment:

selenium:~ auser$ virtualenv new  
New python executable in new/bin/python  
ERROR: The executable new/bin/python is not functioning  
ERROR: It thinks sys.prefix is u'/System/Library/Frameworks/Python.framework/    Versions/2.6' (should be '/Users/user/new')  
ERROR: virtualenv is not compatible with this system or executable  

In my environment:

PYTHONPATH=/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages  
PATH=/System/Library/Frameworks/Python.framework/Versions/2.6/bin:/Library/Frameworks/Python.framework/Versions/2.6/bin:/Library/Frameworks/Python.framework/Versions/2.6/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/usr/X11/bin  

How can I repair this?

Thanks.

Solution 1

If you continue to have trouble with virtualenv, you might try pythonbrew, instead. It's an alternate solution to the same problem. It works more like Ruby's rvm: It builds and creates an entire instance of Python, under $HOME/.pythonbrew, and then sets up some bash functions that allow you to switch easily between versions. Where virtualenv shadows the system version of Python, using symbolic links as part of its solution, pythonbrew builds entirely self-contained installations of Python.

I used virtualenv for years. It's a decent solution, but I've switched to pythonbrew lately. Having completely self-contained Python instances means that installing a new one takes awhile (since pythonbrew actually compiles Python from scratch), but the self-contained nature of each installation appeals to me. And disk is cheap.

Solution 2

Just in case there's someone still seeking for the answer.

I ran into this same problem just today and realized since I already have Anaconda installed, I should not have used pip install virtualenv to install virtual environment as this would give me the error message when trying to initiate it later. Instead, I tried conda install virtualenv then entered virtualenv env_mysite and problem solved.

Solution 3

Like @RyanWilcox mentioned, you might be inadvertently pointing virtualenv to the wrong Python installation. Virtualenv comes with a -p flag to let you specify which interpreter to use.

In my case,

virtualenv test_env

threw the same error as yours, while

virtualenv -p python test_env

worked perfectly.

If you call virtualenv -h, the documentation for the -p flag will tell you which python it thinks it should be using; if it looks wonky, try passing -p python. For reference, I'm on virtualenv 1.11.6.

Solution 4

In case anyone in the future runs into this problem - this is caused by your default Python distribution being conda. Conda has it's own virtual env set up process but if you have the conda distribution of python and still wish to use virtualenv here's how:

1. Find the other python distribution on your machine: ls -ls /usr/bin/python*

2. Take note of the availble python version that is not conda and run the code below (note for python 3 and above you have to upgrade virtualenv first): virtualenv -p python2.7(or your python version) flaskapp

Solution 5

I've run across this problem myself. I wrote down the instructions in a README, which I have pasted below....

I have found there are two things that work:

1. Make sure you're running the latest virtualenv (1.5.1, of this writting)

2. If you're using a non system Python as your standard Python (which python to check) Forcefully use the System supplied one.

   Instead of virtualenv thing use /usr/bin/python2.6 PATH/TO/VIRTUALENV thing (or whatever which python returned to you - this is what it did for me when I ran into this issue)

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Comments

[gigimon]

Not understand, what is bootstrap.py? I'm use system Python: which python /System/Library/Frameworks/Python.framework/Versions/2.6/bin‌​/python

[gigimon]

Thx, I'm try use pythonbew, but later :)

[Jeff]

What's the difference between pythonbrew and virtualenv? Why when I am using pythonbrew I still need to use virtualenv to create isolated env? I asked a question here stackoverflow.com/questions/8256723/…

[Brian Clapper]

Jeff, I added an answer to the question that you referred to. See stackoverflow.com/a/8348440/53495

[Matthew Schinckel]

This fixed my issue: just needed a newer virtualenv.

[KartikKannapur]

I ran into the same error. Did you find a solution?

[Admin]

I just got this error too! Seems like there's no solution. I'm using anaconda, are you guys using the system python or anaconda?

[Jonathan Stray]

Downvoted as I prefer the solution to getting virtualenv working -- for me it was conda install virtualenv as the other answer.

[Chris]

I already had anaconda installed too. I uninstalled from pip and installed with conda: pip uninstall virtualenv -- conda install virtualenv -- virtualenv my_project

[agentcurry]

Worked like a charm. Thank you, kind sir!

[Asanka]

Saved my day. Thank you wastetime909

[nano2nd]

So glad I scrolled down :)

[Oğuz Şerbetci]

python brew is no longer in active development. Do have a look at pyenv, pipenv and pipsi.

[Oduvan]

downvoted (as well as question itself), because what will be the next right answer for this author? "If you continue to have trouble with python, you might try ruby .... "