Gnome terminal will not start

I just tried to install python 3.6 on my Ubuntu 16.04 system, and now I can't run the terminal from the launcher or from Ctrl + Alt + T. I tried to run gnome-terminal from XTerm and got the following message:

Traceback (most recent call last):
  File "/usr/bin/gnome-terminal", line 9, in <module>
    from gi.repository import GLib, Gio
  File "/usr/lib/python3/dist-packages/gi/__init__.py", line 42, in <module>
    from . import _gi
ImportError: cannot import name '_gi'
Error in sys.excepthook:
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/apport_python_hook.py", line 63, in apport_excepthook
    from apport.fileutils import likely_packaged, get_recent_crashes
  File "/usr/lib/python3/dist-packages/apport/__init__.py", line 5, in <module>
    from apport.report import Report
  File "/usr/lib/python3/dist-packages/apport/report.py", line 30, in <module>
    import apport.fileutils
  File "/usr/lib/python3/dist-packages/apport/fileutils.py", line 23, in <module>
    from apport.packaging_impl import impl as packaging
  File "/usr/lib/python3/dist-packages/apport/packaging_impl.py", line 23, in <module>
    import apt
  File "/usr/lib/python3/dist-packages/apt/__init__.py", line 23, in <module>
    import apt_pkg
ModuleNotFoundError: No module named 'apt_pkg'

Original exception was:
Traceback (most recent call last):
  File "/usr/bin/gnome-terminal", line 9, in <module>
    from gi.repository import GLib, Gio
  File "/usr/lib/python3/dist-packages/gi/__init__.py", line 42, in <module>
    from . import _gi
ImportError: cannot import name '_gi'

How can I fix this error?

It should also be noted that:

• My gnome-terminal file is now a python script.
• The gnome-terminal.real file will open the terminal as expected.
• python3.5 gnome-terminal will open the terminal as expected.

Probably the symlink /usr/bin/python3 points to python3.6, which it should not. Fix it by running these commands:

sudo rm /usr/bin/python3
sudo ln -s python3.5 /usr/bin/python3

You don't have to point Python3 to python3.5 , just running the commands:

cd /usr/lib/python3/dist-packages/gi/
sudo cp _gi.cpython-35m-x86_64-linux-gnu.so _gi.cpython-36m-x86_64-linux-gnu.so
sudo cp _gi_cairo.cpython-35m-x86_64-linux-gnu.so _gi_cairo.cpython-36m-x86_64-linux-gnu.so

Proper change of default python3 is done via:

sudo update-alternatives --config python3

Although copying the _gi_cairo.cpython-35m-x86_64-linux-gnu.so from python3.5 to python3.6 could resolve the issue, but would break your library consistency. And should be avoided.

I know this is an old question but for those looking for a way other than changing python3 to python 3.5 globally, you can change the first line of /usr/bin/gnome-terminal from #! /usr/bin/python3 to #! /usr/bin/python3.5.

Note: I don't have python 3.5 on my computer but import gi works in python 3.6, so used 3.6 instead of 3.5.