Ubuntu Server 16.04 installs on /sdc but fails to boot
I noticed the same behavior with 16.04 net install.
If your issue is the same as mine, it actually booted fine it's just showing you tty7.
Try hitting ctrl+alt+F1 that should take you to the terminal with a login prompt.
I had the same problem last night with Ubuntu 15.10. Turned out I knocked out a SATA connector on a (secondary) drive. No actual error is output here, which was quite confusing until I opened up and noticed the connector out of place.
Leads me to think that for you it’s looking for the flash drive using some sort of identifier that in some way has changed between the live USB boot and the boot of the installed system, or you just haven’t tried booting with the drive attached.
Boot a live OS (you should be able to get away with reusing your Ubuntu Server flash drive – hit Alt→ to get to a command line). Get a list of disks and partitions:
# fdisk -l | less
Obviously it’ll be on sdc, but determine which partition is the ext4 system one.
Mount the partition (assuming sdc2):
# mkdir /mnt/ssd
# mount /dev/sdc2 /mnt/ssd
Now inspect its fstab:
# nano /mnt/ssd/etc/fstab
If this is a UEFI install, you should probably only have lines for the EFI system partition (/boot/efi), the boot partition (/boot), and the system root (/). The setup helpfully annotates the lines it made in the generated fstab, so anything not on /dev/sdc* should be removed (or just comment it out to be safe).
Save that (CtrlX, Y, Enter), and do
# sync
# reboot
to ensure changes are committed to disk and reboot. Disconnect the flash drive and see how it goes.
A few common reasons I’ve seen flash drives appear before the system drive are due to a BIOS setting being used that allows you to fake the drive to another type (floppy drive, hard drive, etc) rather than relying on the drive’s own identification, or because the drive has had the removable bit turned off. Are you using the same drive for the 14.04 installer as you are for 16.04? If you’re certain it’s not on your end then it does sound like an OS bug.
You are mislead by the sda/sdc issue. Your fstab shows that the machine assigns file systems per UUID, and on top of that, the fsck line shows that grub could start the initrd which did the initial filecheck.
It could be something as simple as wrong graphics setting for the kernel. Basically, you can't see the ttys, and X is not on your server, correct?
Try and add nomodeset to the GRUB_CMDLINE_LINUX_DEFAULT="quiet splash" line in /etc/default/grub, and also add a line GRUB_GFXPAYLOAD_LINUX=keep.
I had two systems with 16.04 showing similar symptoms as you describe, but since they could boot to X, I could fix it in a running system. It was very similar, I saw the fsck line (on tty1) or nothing at all (on tty2-6).