Can't open system settings

[DJ Lolek]

In fully updated Linux Mint 18 I suddenly noticed that I can't open Sound Settings.
I decided to go to sound settings trough System Settings, but then even System Settings did not open.
I opened terminal and ran "cinnamon-settings"
this was the result:

user@user-PC ~ $ cinnamon-settings
Traceback (most recent call last):
  File "/usr/share/cinnamon/cinnamon-settings/cinnamon-settings.py", line 12, in <module>
    import gi
ImportError: No module named gi

Ok, did something mess with my python?

user-PC user # apt-get install python-gi
Reading package lists... Done
Building dependency tree
Reading state information... Done
python-gi is already the newest version (3.20.0-0ubuntu1).
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

and then I try running "cinnamon-settings" as root and it works fine.

I really don't want to log in as root every time I want to change volume of specific application.

[Reiner (rschulz-gmail)]

in my case, was caused by competing python installation (as part of anaconda). cinnamon behaved normally after removal of anaconda/bin from PATH.

[Simon Grantham (grantham)]

I have as yet been unable to find the path through. My path is:

    user@user-pc ~ $ echo $PATH
    /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games

I upgraded to mint 18, but I don't know if the problem existed before I upgraded python as I was in the middle of dev.

    user@user-pc /usr/bin $ python --version
    Python 2.7.12

Attempted to reinstall:

    user@user-pc ~ $ sudo apt-get install --reinstall python-gi
    Reading package lists... Done
    Building dependency tree
    Reading state information... Done
    The following packages were automatically installed and are no longer required:
      fonts-noto fonts-noto-hinted g++-4.8 grilo-plugins-0.2-base language-selector-common libctemplate2 libdbd-mysql-perl libdbi-perl libglew1.10 libgom-1.0-0
      libgom-1.0-common libmediaart-2.0-0 libmkv0 libmusicbrainz5-0 libmysqlclient20 libpeas-1.0-0-python3loader libsctp1 libstdc++-4.8-dev libsvga1
      libterm-readkey-perl libtinyxml2.6.2 libtracker-sparql-1.0-0 libwireshark3 libwiretap3 libwsutil3 libwxbase2.8-0 libwxgtk2.8-0 libxerces2-java
      libxml-commons-external-java mint-backgrounds-rosa mint-kernel-info phonon-backend-gstreamer1.0 xchat-common
    Use 'sudo apt autoremove' to remove them.
0 upgraded, 0 newly installed, 1 reinstalled, 0 to remove and 27 not upgraded.
    Need to get 0 B/194 kB of archives.
    After this operation, 0 B of additional disk space will be used.
(Reading database ... 274625 files and directories currently installed.)
    Preparing to unpack .../python-gi_3.20.0-0ubuntu1_amd64.deb ...
    Unpacking python-gi (3.20.0-0ubuntu1) over (3.20.0-0ubuntu1) ...
    Setting up python-gi (3.20.0-0ubuntu1) ...

Check...

    user@user-pc ~ $ apt policy python python-gi
    python:
      Installed: 2.7.11-1
      Candidate: 2.7.11-1
      Version table:
     *** 2.7.11-1 500
        500 http://archive.ubuntu.com/ubuntu xenial/main amd64 Packages
        100 /var/lib/dpkg/status
    python-gi:
      Installed: 3.20.0-0ubuntu1
      Candidate: 3.20.0-0ubuntu1
      Version table:
     *** 3.20.0-0ubuntu1 500
            500 http://archive.ubuntu.com/ubuntu xenial/main amd64 Packages
            100 /var/lib/dpkg/status

Test...

    user@user-pc ~ $ cinnamon-settings
    Traceback (most recent call last):
      File "/usr/share/cinnamon/cinnamon-settings/cinnamon-settings.py", line 12, in <module>
        import gi
    ImportError: No module named gi

su Test...

    user@user-pc ~ $ sudo cinnamon-settings
    Traceback (most recent call last):
      File "/usr/share/cinnamon/cinnamon-settings/cinnamon-settings.py", line 12, in <module>
        import gi
    ImportError: No module named gi

No luck. I continue to search...

[Simon Grantham (grantham)]

Addendum:

user@user-pc ~ $ ls -l /usr/bin | grep python
lrwxrwxrwx 1 root root 26 May 18 05:10 dh_pypy -> ../share/dh-python/dh_pypy
-rwxr-xr-x 1 root root 1056 Dec 9 2015 dh_python2
lrwxrwxrwx 1 root root 29 May 18 05:10 dh_python3 -> ../share/dh-python/dh_python3
lrwxrwxrwx 1 root root 23 Jul 2 15:05 pdb2.7 -> ../lib/python2.7/pdb.py
lrwxrwxrwx 1 root root 23 Sep 14 17:25 pdb3.5 -> ../lib/python3.5/pdb.py
lrwxrwxrwx 1 root root 31 Mar 23 2016 py3versions -> ../share/python3/py3versions.py
lrwxrwxrwx 1 root root 26 May 18 05:10 pybuild -> ../share/dh-python/pybuild
lrwxrwxrwx 1 root root 9 Dec 9 2015 python -> python2.7
lrwxrwxrwx 1 root root 9 Dec 9 2015 python2 -> python2.7
-rwxr-xr-x 1 root root 3546104 Jul 2 15:05 python2.7
lrwxrwxrwx 1 root root 33 Jul 2 15:05 python2.7-config -> x86_64-linux-gnu-python2.7-config
lrwxrwxrwx 1 root root 16 Dec 9 2015 python2-config -> python2.7-config
lrwxrwxrwx 1 root root 9 Mar 23 2016 python3 -> python3.5
-rwxr-xr-x 2 root root 4464432 Sep 14 17:25 python3.5
-rwxr-xr-x 2 root root 4464432 Sep 14 17:25 python3.5m
lrwxrwxrwx 1 root root 10 Mar 23 2016 python3m -> python3.5m
lrwxrwxrwx 1 root root 16 Dec 9 2015 python-config -> python2.7-config
lrwxrwxrwx 1 root root 29 Dec 9 2015 pyversions -> ../share/python/pyversions.py
-rwxr-xr-x 1 root root 2909 Jul 2 15:02 x86_64-linux-gnu-python2.7-config
lrwxrwxrwx 1 root root 33 Dec 9 2015 x86_64-linux-gnu-python-config -> x86_64-linux-gnu-python2.7-config