Comment 11 for bug 1573720

I can report the same issue in Linux Mint 18, where both the packages mentioned by Steve MacDougall are in place:

[ root ] dpkg -l wpasupplicant network-manager-gnome gz-Latitude-E7240:~
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name Version Architecture Description
+++-===========================-==================-==================-============================================================
ii network-manager-gnome 1.2.0-0ubuntu0.16. amd64 network management framework (GNOME frontend)
ii wpasupplicant 2.4-0ubuntu6 amd64 client support for WPA and WPA2 (IEEE 802.11i)

This was not a problem in Linux Mint 17.3, where network-manager-gnome was in version 0.9.8.8-0ubuntu4.1-mint1, and wpasupplicant doesn't seem to be part of the default release.

Was able to implement a workaround by forcing a downgrade of network-manager-gnome:
$ sudo su -
# service network-manager stop
# dpkg --force-all -i network-manager-gnome_0.9.8.8-0ubuntu4.1-mint1_amd64.deb
# service network-manager start

it works for me! :)