Ubuntu – UUID=xxx does not exist. Dropping to a shell

bootfstabgrub2mount

Because of a hardware failure my motherboard has just been replaced. After the replacement, my system (Ubuntu 17.10) doesn't boot:

ALERT! UUID=dd84f4b3-d5bf-42e4-9b5e-ec685a461fad does not exist.
Dropping to a shell.

I've used a Live USB Ubuntu to debug this problem. Here are some results:

/etc/fstab

# /etc/fstab: static file system information.
#
# Use 'blkid' to print the universally unique identifier for a
# device; this may be used with UUID= as a more robust way to name devices
# that works even if disks are added and removed. See fstab(5).
#
# <file system> <mount point>   <type>  <options>       <dump>  <pass>
# / was on /dev/nvme0n1p3 during installation
UUID=dd84f4b3-d5bf-42e4-9b5e-ec685a461fad /               ext4    errors=remount-ro 0       1

# /boot/efi was on /dev/nvme0n1p1 during installation
UUID=B38D-559B  /boot/efi       vfat    umask=0077      0       1
# swap was on /dev/nvme0n1p4 during installation
UUID=f4134c38-10b9-478f-b550-54650a9f5140 none            swap    sw              0       0

blkid

/dev/nvme0n1p1: SEC_TYPE="msdos" UUID="B38D-559B" TYPE="vfat" PARTLABEL="EFI System Partition" PARTUUID="98be6c97-c354-49a6-a432-9201d56a421b"
/dev/nvme0n1p2: LABEL="OS" UUID="B39E-7035" TYPE="vfat" PARTLABEL="fat32" PARTUUID="d3006358-8d82-4e0b-99f8-87a5261cf7e8"
/dev/nvme0n1p3: LABEL="UBUNTU" UUID="dd84f4b3-d5bf-42e4-9b5e-ec685a461fad" TYPE="ext4" PARTUUID="24e5b96d-f20c-43dd-9e48-672760b0e6f7"
/dev/sda1: LABEL="UBUNTU 17_1" UUID="88D4-322D" TYPE="vfat" PARTUUID="3d0a270b-01"

fdisk -l

Disk /dev/loop0: 1.3 GiB, 1427259392 bytes, 2787616 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/nvme0n1: 477 GiB, 512110190592 bytes, 1000215216 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: 43E35EBE-2A73-404A-9D4A-851815F33F9A

Device             Start        End   Sectors   Size Type
/dev/nvme0n1p1        34     488281    488248 238.4M EFI System
/dev/nvme0n1p2    488282    5934980   5446699   2.6G Microsoft basic data
/dev/nvme0n1p3   5935104  933576703 927641600 442.3G Linux filesystem
/dev/nvme0n1p4 933576704 1000214527  66637824  31.8G Linux swap


Disk /dev/sda: 28.7 GiB, 30752636928 bytes, 60063744 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x3d0a270b

Device     Boot Start      End  Sectors  Size Id Type
/dev/sda1  *     2048 60063743 60061696 28.7G  c W95 FAT32 (LBA)

It looks like the UUID's in fstab are correct, but I still get that error message.

How can I repair my Ubuntu installation?

I've tried the given solution in ALERT! /dev/disk/by-uuid/xxxxxxxxx does not exist. Dropping to a shell, but unfortunately that didn't help (I mounted /dev/nvme0n1p3). Still the same problem.

Update:
When I select UEFI boot mode in system setup, I still get this problem. But when I select legacy boot I got 'no boot device found'. But here comes the tricky part: when I select legacy mode and use F12 to select UEFI/Ubuntu, it starts without a problem.

Best Answer

When I tried to use a pendrive Ubuntu to figure out this problem, I finally found out that the hard drive wasn't recognized when Legacy Boot was disabled. This explained why manually choosing UEFI did work.

The problem was that the new motherboard had the default settings, so RAID was enabled. Switching to AHCI solved my problem. This were the steps needed to change it: (borrowed from This answer)

  1. Boot into BIOS (F12 at startup)
  2. Select Bios Setup
  3. Move to System Configuration→SATA Operation and select AHCI
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