Comment 8 for bug 1435774

> # system bring up correctly
Do you recall seeing any errors on boot when you first booted the image written using ubuntu-device-flash?

Is it possible you had previously attempted to update from 185 -> 186 and the power failed or the device was unplugged?

If not, either your media has "gone bad", or was always bad but you were lucky enough to boot from the "system-a" partition initially.

To resolve the situation, you have a few options. Tthe normal caveats apply - if I were you, I'd back up any writable data you have on the device before proceeding:

(1) Run fsck manually:

# check that the partition really is one of the read-only rootfs's first
$ sudo blkid|grep "/dev/mmcblk0p2.*LABEL=\"system-a\"" && echo OK || echo FAIL

$ sudo umount /dev/mmcblk0p2
$ sudo fsck -M -yv /dev/mmcblk0p2
(answer any prompts - the 'y' option should do everything for you though)
$ sudo reboot
$ sudo snappy-go update

(2) Reformat the "system-a" rootfs:

# check that the partition really is one of the read-only rootfs's first
$ sudo blkid|grep "/dev/mmcblk0p2.*LABEL=\"system-a\"" && echo OK || echo FAIL

$ sudo umount /dev/mmcblk0p2
$ sudo mkfs.ext4 -v -L system-a /dev/mmcblk0p2
$ sudo reboot
$ sudo snappy-go update

(3) Reflash the entire disk using ubuntu-device-flash

(4) Flash an image to a different disk using ubuntu-device-flash.