Preparing to unpack .../flashplugin-installer_24.0.0.221ubuntu0.16.04.1_amd64.deb ...
Unpacking flashplugin-installer (24.0.0.221ubuntu0.16.04.1) over (24.0.0.194ubuntu0.16.04.1) ...
Preparing to unpack .../libgc1c2_1%3a7.4.2-7.3ubuntu0.1_amd64.deb ...
Unpacking libgc1c2:amd64 (1:7.4.2-7.3ubuntu0.1) over (1:7.4.2-7.3) ...
Processing triggers for update-notifier-common (3.168.3) ...
Traceback (most recent call last):
  File "/usr/lib/update-notifier/package-data-downloader", line 24, in <module>
    import debian.deb822
  File "/usr/lib/python3/dist-packages/debian/deb822.py", line 47, in <module>
    import six
ImportError: No module named 'six'
dpkg: error processing package update-notifier-common (--unpack):
 subprocess installed post-installation script returned error exit status 1