System update almost broke the system [duplicate]
I got the exact same problem. Downgraded to 4.4.0-38, then blocked -39 from being installed, by pinning that version with priority -1. This is a kernel regression, which might show up in later 4.4.0 updates too. Hopefully it is fixed in the kernel version shipping with Ubuntu 16.10. The -39 kernel fails to detect my NVMe SSD that I'm booting from, while the -38 kernel works perfectly. According to the release notes there were two fixes to the NVMe code: (LP: #1602724) and (LP: #1620317). It is possible one of these broke the NVMe detection.