pip installed but throwing error while installing any package

Question

pip is installed on my system but whenever I try to install any package it throws below exception. Same exception comes on installing each and every package. I could not find this anywhere on web. Please help.

pip install django-social-auth
Downloading/unpacking django-social-auth
Cleaning up...
Exception:
Traceback (most recent call last):
  File "/Library/Python/2.7/site-packages/pip-1.5.2-py2.7.egg/pip/basecommand.py", line 122, in main
   status = self.run(options, args)
  File "/Library/Python/2.7/site-packages/pip-1.5.2-py2.7.egg/pip/commands/install.py", line 274, in run
   requirement_set.prepare_files(finder, force_root_egg_info=self.bundle, bundle=self.bundle)
  File "/Library/Python/2.7/site-packages/pip-1.5.2-py2.7.egg/pip/req.py", line 1166, in prepare_files
   url = finder.find_requirement(req_to_install, upgrade=self.upgrade)
 File "/Library/Python/2.7/site-packages/pip-1.5.2-py2.7.egg/pip/index.py", line 194, in find_requirement
  page = self._get_page(main_index_url, req)
 File "/Library/Python/2.7/site-packages/pip-1.5.2-py2.7.egg/pip/index.py", line 568, in _get_page
  session=self.session,
 File "/Library/Python/2.7/site-packages/pip-1.5.2-py2.7.egg/pip/index.py", line 670, in get_page
   resp = session.get(url, headers={"Accept": "text/html"})
 File "/Library/Python/2.7/site-packages/pip-1.5.2-py2.7.egg/pip/_vendor/requests/sessions.py", line 395, in get
   return self.request('GET', url, **kwargs)
 File "/Library/Python/2.7/site-packages/pip-1.5.2-py2.7.egg/pip/download.py", line 237, in request
   return super(PipSession, self).request(method, url, *args, **kwargs)
  File "/Library/Python/2.7/site-packages/pip-1.5.2-py2.7.egg/pip/_vendor/requests/sessions.py", line 356, in request
    env_proxies = get_environ_proxies(url) or {}
  File "/Library/Python/2.7/site-packages/pip-1.5.2-py2.7.egg/pip/_vendor/requests/utils.py", line 504, in get_environ_proxies
    bypass = proxy_bypass(netloc)
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/urllib.py", line 1433, in proxy_bypass
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/urllib.py", line 1413, in proxy_bypass_macosx_sysconf
ValueError: negative shift count

Answer 1

The urllib module used by pip will automatically load proxy configuration from your OS.

In this case, this fails because you appear to have some malformed proxy configuration, in the proxy-bypass field. Verify that your proxy configuration is correct. On Mac, do so under System Preferences > Network.

Answer 2

Bypass proxy settings hosts section. i removed them and its working fine now. ----This worked for me as well

Answer 3

If @Martijn Pieters' answer doesn't fix it for you, be sure to check the "Bypass proxy settings hosts" section.

Try removing the addresses in that field, click apply changes and try again.