pip3 install not working - No module named 'pip._vendor.pkg_resources'

When trying to install a package for Python 3 (in Ubuntu), using pip3 install packageName (or sudo pip3 install packageName), I get the following error message:

Traceback (most recent call last):  File "/usr/lib/python3/dist-packages/pip/_vendor/__init__.py", line 33, in vendored    __import__(vendored_name, globals(), locals(), level=0)ImportError: No module named 'pip._vendor.pkg_resources'

I have been reading for days and have tried the following WITHOUT any success:

1. Un-installing and re-installing pip3 using the following code: sudo apt-get remove python3-pip followed by sudo apt-get install python3-pip. This was suggested in several posts that say that sometimes pip3 doesn't install properly for Ubuntu. However, it didn't work.
2. Other post suggested it was an ssl package problem and that if the ssl package doesn't load on Python3, that's the issue. However the following command does not raise any error: python3 -c "import ssl".
3. Some other post suggested the problem was with the requests package. I then tried sudo apt-get remove python3-requests followed by sudo apt-get install python3-requests also to no avail.

Other information you may need:

• pip3 --version gives me the same error reported above.

• dpkg -L python3-pip gives me the following information:

  /./usr/usr/lib/usr/lib/python3/usr/lib/python3/dist-packages/usr/lib/python3/dist-packages/pip-8.1.1.egg-info/usr/lib/python3/dist-packages/pip-8.1.1.egg-info/PKG-INFO/usr/lib/python3/dist-packages/pip-8.1.1.egg-info/dependency_links.txt/usr/lib/python3/dist-packages/pip-8.1.1.egg-info/not-zip-safe/usr/lib/python3/dist-packages/pip-8.1.1.egg-info/requires.txt/usr/lib/python3/dist-packages/pip-8.1.1.egg-info/entry_points.txt/usr/lib/python3/dist-packages/pip-8.1.1.egg-info/top_level.txt/usr/lib/python3/dist-packages/pip/usr/lib/python3/dist-packages/pip/baseparser.py/usr/lib/python3/dist-packages/pip/__main__.py/usr/lib/python3/dist-packages/pip/req/usr/lib/python3/dist-packages/pip/req/req_set.py/usr/lib/python3/dist-packages/pip/req/req_install.py/usr/lib/python3/dist-packages/pip/req/__init__.py/usr/lib/python3/dist-packages/pip/req/req_file.py/usr/lib/python3/dist-packages/pip/req/req_uninstall.py/usr/lib/python3/dist-packages/pip/index.py/usr/lib/python3/dist-packages/pip/status_codes.py/usr/lib/python3/dist-packages/pip/utils/usr/lib/python3/dist-packages/pip/utils/setuptools_build.py/usr/lib/python3/dist-packages/pip/utils/appdirs.py/usr/lib/python3/dist-packages/pip/utils/outdated.py/usr/lib/python3/dist-packages/pip/utils/ui.py/usr/lib/python3/dist-packages/pip/utils/logging.py/usr/lib/python3/dist-packages/pip/utils/encoding.py/usr/lib/python3/dist-packages/pip/utils/deprecation.py/usr/lib/python3/dist-packages/pip/utils/__init__.py/usr/lib/python3/dist-packages/pip/utils/filesystem.py/usr/lib/python3/dist-packages/pip/utils/hashes.py/usr/lib/python3/dist-packages/pip/utils/build.py/usr/lib/python3/dist-packages/pip/compat/usr/lib/python3/dist-packages/pip/compat/dictconfig.py/usr/lib/python3/dist-packages/pip/compat/__init__.py/usr/lib/python3/dist-packages/pip/compat/ordereddict.py/usr/lib/python3/dist-packages/pip/models/usr/lib/python3/dist-packages/pip/models/index.py/usr/lib/python3/dist-packages/pip/models/__init__.py/usr/lib/python3/dist-packages/pip/vcs/usr/lib/python3/dist-packages/pip/vcs/bazaar.py/usr/lib/python3/dist-packages/pip/vcs/subversion.py/usr/lib/python3/dist-packages/pip/vcs/mercurial.py/usr/lib/python3/dist-packages/pip/vcs/__init__.py/usr/lib/python3/dist-packages/pip/vcs/git.py/usr/lib/python3/dist-packages/pip/cmdoptions.py/usr/lib/python3/dist-packages/pip/basecommand.py/usr/lib/python3/dist-packages/pip/commands/usr/lib/python3/dist-packages/pip/commands/completion.py/usr/lib/python3/dist-packages/pip/commands/install.py/usr/lib/python3/dist-packages/pip/commands/hash.py/usr/lib/python3/dist-packages/pip/commands/uninstall.py/usr/lib/python3/dist-packages/pip/commands/__init__.py/usr/lib/python3/dist-packages/pip/commands/list.py/usr/lib/python3/dist-packages/pip/commands/search.py/usr/lib/python3/dist-packages/pip/commands/show.py/usr/lib/python3/dist-packages/pip/commands/download.py/usr/lib/python3/dist-packages/pip/commands/wheel.py/usr/lib/python3/dist-packages/pip/commands/freeze.py/usr/lib/python3/dist-packages/pip/commands/help.py/usr/lib/python3/dist-packages/pip/_vendor/usr/lib/python3/dist-packages/pip/_vendor/__init__.py/usr/lib/python3/dist-packages/pip/operations/usr/lib/python3/dist-packages/pip/operations/__init__.py/usr/lib/python3/dist-packages/pip/operations/freeze.py/usr/lib/python3/dist-packages/pip/__init__.py/usr/lib/python3/dist-packages/pip/locations.py/usr/lib/python3/dist-packages/pip/pep425tags.py/usr/lib/python3/dist-packages/pip/exceptions.py/usr/lib/python3/dist-packages/pip/download.py/usr/lib/python3/dist-packages/pip/wheel.py/usr/share/usr/share/man/usr/share/man/man1/usr/share/man/man1/pip3.1.gz/usr/share/doc/usr/share/doc/python3-pip/usr/share/doc/python3-pip/copyright/usr/bin/usr/bin/pip3/usr/share/doc/python3-pip/changelog.Debian.gz

How can I make pip3 work?

NOTE: pip for Python2 works just fine.

================================================

EDIT:

1. When trying to import setuptools in Python3 I get the following error:

    Traceback (most recent call last):      File "<stdin>", line 1, in <module>      File "/usr/lib/python3/dist-packages/setuptools/__init__.py", line 11, in <module>        from setuptools.extern.six.moves import filterfalse, map      File "/usr/lib/python3/dist-packages/setuptools/extern/__init__.py", line 1, in <module>        from pkg_resources.extern import VendorImporter      File "/usr/lib/python3/dist-packages/pkg_resources/__init__.py", line 2927, in <module>        @_call_aside      File "/usr/lib/python3/dist-packages/pkg_resources/__init__.py", line 2913, in _call_aside        f(*args, **kwargs)      File "/usr/lib/python3/dist-packages/pkg_resources/__init__.py", line 2952, in _initialize_master_working_set        add_activation_listener(lambda dist: dist.activate())      File "/usr/lib/python3/dist-packages/pkg_resources/__init__.py", line 956, in subscribe        callback(dist)      File "/usr/lib/python3/dist-packages/pkg_resources/__init__.py", line 2952, in <lambda>        add_activation_listener(lambda dist: dist.activate())      File "/usr/lib/python3/dist-packages/pkg_resources/__init__.py", line 2515, in activate        declare_namespace(pkg)      File "/usr/lib/python3/dist-packages/pkg_resources/__init__.py", line 2097, in declare_namespace        _handle_ns(packageName, path_item)      File "/usr/lib/python3/dist-packages/pkg_resources/__init__.py", line 2047, in _handle_ns        _rebuild_mod_path(path, packageName, module)      File "/usr/lib/python3/dist-packages/pkg_resources/__init__.py", line 2066, in _rebuild_mod_path        orig_path.sort(key=position_in_sys_path)    AttributeError: '_NamespacePath' object has no attribute 'sort'

2. When running the following command sed -n '31,37p'< /usr/lib/python3/dist-packages/pip/_vendor/__init__.py in the terminal, I get the following:

   try:    __import__(vendored_name, globals(), locals(), level=0)except ImportError:    try:        __import__(modulename, globals(), locals(), level=0)    except ImportError:

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EDIT2:

My python3 --version is Python 3.5.2.

List of installed packages obtained running the code ls /usr/lib/python3/dist-packages.

apportapport_python_hook.pyaptaptdaemonapt_inst.cpython-35m-x86_64-linux-gnu.soapt_pkg.cpython-35m-x86_64-linux-gnu.soaptsourcesAptUrlapturl-0.5.2.egg-infobeautifulsoup4-4.4.1.egg-infoblinkerblinker-1.3.egg-infoBrlapi-0.6.4.egg-infobrlapi.cpython-35m-x86_64-linux-gnu.sobs4cairo_cffi_backend.cpython-35m-x86_64-linux-gnu.sochardetchardet-2.3.0.egg-infocheckbox_supportcheckbox_support-0.22.egg-infoCommandNotFoundcommand_not_found-0.3.egg-infocryptographycryptography-1.2.3.egg-infocups.cpython-35m-x86_64-linux-gnu.socupsext.cpython-35m-x86_64-linux-gnu.socurlcycler-0.9.0.egg-infocycler.pydateutildbus_dbus_bindings.cpython-35m-x86_64-linux-gnu.so_dbus_glib_bindings.cpython-35m-x86_64-linux-gnu.sodeb822.pydebconf.pydebiandebian_bundledecorator-4.0.6.egg-infodecorator.pydeferdefer-1.0.6.egg-infoDistUpgradeeasy_install.pyfeedparser-5.1.3.egg-infofeedparser.pyfeedparser_sgmllib3.pygiguacamoleguacamole-0.9.2.egg-infohpmudext.cpython-35m-x86_64-linux-gnu.sohtml5libhtml5lib-0.999.egg-infohttplib2httplib2-0.9.1.egg-infoidnaidna-2.0.egg-infojanitorjinja2Jinja2-2.8.egg-infojwtLanguageSelectorlanguage_selector-0.1.egg-infolanguage_support_pkgs.pylouislouis-2.6.4.egg-infolsb_release.pylxmllxml-3.5.0.egg-infomakoMako-1.0.3.egg-infomarkupsafeMarkupSafe-0.23.egg-infomatplotlibmatplotlib-1.5.1.egg-infomatplotlib-1.5.1-nspkg.pthmpl_toolkitsnetworkxnetworkx-1.11.egg-infonumexprnumexpr-2.4.3.egg-infonumpynumpy-1.11.0.egg-infoNvidiaDetectoroauthliboauthlib-1.0.3.egg-infoOnboardonboard-1.2.0.egg-infoorcapadmepadme-1.1.1.egg-infopandaspandas-0.17.1.egg-infopcardext.cpython-35m-x86_64-linux-gnu.sopexpectpexpect-4.0.1.egg-infoPILPillow-3.1.2.egg-infopippip-8.1.1.egg-infopkg_resourcesplotlyplotly-1.9.5.egg-infoproblem_report.pyptyprocessptyprocess-0.5.egg-infopyasn1pyasn1-0.1.9.egg-infopyatspi__pycache__pycups-1.9.73.egg-infopycurl-7.43.0.egg-infopycurl.cpython-35m-x86_64-linux-gnu.sopygobject-3.20.0.egg-infopygtkcompatPyJWT-1.3.0.egg-infopylab.pypyparsing-2.0.3.egg-infopyparsing.pypython_apt-1.1.0.b1_ubuntu0.16.04.1.egg-infopython_dateutil-2.4.2.egg-infopython_debian-0.1.27.egg-infopython_systemd-231.egg-infopytzpytz-2014.10.egg-infopyxdg-0.25.egg-infoPyYAML-3.11.egg-infoQuirksreportlabreportlab-3.3.0.egg-inforequestsrequests-2.9.1.egg-infoscanext.cpython-35m-x86_64-linux-gnu.soscipyscipy-0.17.0.egg-infosessioninstallersessioninstaller-0.0.0.egg-infosetuptoolssetuptools-20.7.0.egg-infosix-1.10.0.egg-infosix.pysoftwarepropertiesspeechdspeechd_configsystemdsystem_service-0.3.egg-infotablestables-3.2.2.egg-infoUbuntuDriversubuntu_drivers_common-0.0.0.egg-infoUbuntuSystemServiceufwufw-0.35.egg-infounattended_upgrades-0.1.egg-infounity_scope_calculator-0.1.egg-infounity_scope_chromiumbookmarks-0.1.egg-infounity_scope_colourlovers-0.1.egg-infounity_scope_devhelp-0.1.egg-infounity_scope_firefoxbookmarks-0.1.egg-infounity_scope_gdrive-0.7.egg-infounity_scope_manpages-0.1.egg-infounity_scope_openclipart-0.1.egg-infounity_scope_texdoc-0.1.egg-infounity_scope_tomboy-0.1.egg-infounity_scope_virtualbox-0.1.egg-infounity_scope_yelp-0.1.egg-infounity_scope_zotero-0.1.egg-infounohelper.pyuno.pyUpdateManagerurllib3urllib3-1.13.1.egg-infousbcreatorusb_creator-0.3.0.egg-infowheelwheel-0.29.0.egg-infoxdgxdiagnosexdiagnose-3.8.4.1.egg-infoxkitxkit-0.0.0.egg-infoxlsxwriterXlsxWriter-0.7.3.egg-infoyaml_yaml.cpython-35m-x86_64-linux-gnu.so