I recently updated my kernel on my 14.04 install to the Xenial LTS kernel, and encountered the same issue. See: http://askubuntu.com/questions/786328/14-04-3-lts-xenial-kernel-upgrade-nvme-ssd-wont-boot
I recently updated my kernel on my 14.04 install to the Xenial LTS kernel, and encountered the same issue. See: http:// askubuntu. com/questions/ 786328/ 14-04-3- lts-xenial- kernel- upgrade- nvme-ssd- wont-boot