I had the same issue but I fixed It after adding this line stop on runlevel [6] into the file /etc/init/network-manager.conf. I've never had this issue since I added the line.
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/869635 Title: long delay at shutdown/reboot - network-manager doesn't close correctly To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/network-manager/+bug/869635/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs