Comment 2 for bug 1513437

There are several components at play here, apart from the vpnc package there's vpnc-scripts as well as network-manager-vpnc{-gnome}. None of these changed between 15.04 and 15.10. What did change is network-manager itself (from 0.9.10.0-4ubuntu15.1 to 1.0.4-0ubuntu5) and I suspect the network-manager-vpnc package lacks adaptation to handle your case properl. Hence I'm reassigning this bug.