Why does Virt-P2V failed with "virt-p2v had shutdown unexpectedly" or "The connection's MAC address did not match this device." ?

Issue

• Virt-P2V failed with following error :

virt-p2v had shutdown unexpectedly
　Try running it again
　Debug virt-p2v
　Power the machine off

• P2V logs the following error in dmesg .

(eval):30:in `ActivateConnection': org.freedesktop.NetworkManager.ConnectionIncompatible: The connection's MAC address did not match this device.
         from /usr/lib/ruby/site_ruby/1.8/dbus/bus.rb:535:in `call'
         from /usr/lib/ruby/site_ruby/1.8/dbus/bus.rb:535:in `process'
         from /usr/lib/ruby/site_ruby/1.8/dbus/bus.rb:493:in `send_sync'
        from (eval):28:in `ActivateConnection'
         from /usr/lib/ruby/site_ruby/1.8/dbus/introspect.rb:494:in `call'
         from /usr/lib/ruby/site_ruby/1.8/dbus/introspect.rb:494:in `method_missing'
         from /usr/lib/ruby/gems/1.8/gems/virt-p2v-0.8.6/lib/virt-p2v/netdevice.rb:125:in `activate'
         from /usr/lib/ruby/gems/1.8/gems/virt-p2v-0.8.6/lib/virt-p2v/ui/network.rb:226:in `network_button_clicked'
         from /usr/lib/ruby/gems/1.8/gems/gtk2-1.0.3/lib/gtk2/base.rb:94:in `call'
         from /usr/lib/ruby/gems/1.8/gems/gtk2-1.0.3/lib/gtk2/base.rb:94:in `__connect_signals__'
         from /usr/lib/ruby/gems/1.8/gems/virt-p2v-0.8.6/lib/virt-p2v/gtk-queue.rb:50:in `call'
         from /usr/lib/ruby/gems/1.8/gems/virt-p2v-0.8.6/lib/virt-p2v/gtk-queue.rb:50:in `main'
         from /usr/lib/ruby/gems/1.8/gems/virt-p2v-0.8.6/lib/virt-p2v/gtk-queue.rb:50:in `main_with_queue'
         from /usr/lib/ruby/gems/1.8/gems/virt-p2v-0.8.6/lib/virt-p2v/ui/main.rb:54:in `main_loop'
         from /usr/lib/ruby/gems/1.8/gems/virt-p2v-0.8.6/bin/virt-p2v:56
         from /usr/bin/virt-p2v:19:in `load'
         from /usr/bin/virt-p2v:19