I have the same problem.
(nm-connection-editor:6624): Gtk-CRITICAL **: gtk_list_store_get_value: assertion `VALID_ITER (iter, list_store)' failed
(nm-connection-editor:6624): GLib-GObject-WARNING **: /build/buildd/glib2.0-2.18.2/gobject/gtype.c:3940: type id `0' is invalid
(nm-connection-editor:6624): GLib-GObject-WARNING **: can't peek value table for type `<invalid>' which is not currently referenced Segmentation fault
I have the same problem.
(nm-connection- editor: 6624): Gtk-CRITICAL **: gtk_list_ store_get_ value: assertion `VALID_ITER (iter, list_store)' failed
(nm-connection- editor: 6624): GLib-GObject- WARNING **: /build/ buildd/ glib2.0- 2.18.2/ gobject/ gtype.c: 3940: type id `0' is invalid
(nm-connection- editor: 6624): GLib-GObject- WARNING **: can't peek value table for type `<invalid>' which is not currently referenced
Segmentation fault