In this article we’ll show how to solve problems that occur when a computer running Linux Ubuntu/Mint/Kali doesn’t boot or drops to a busybox?prompt during the initramfs initialization. The user can access and use only the initramfs command prompt.

Repairing a broken Ext4 Superblock in LInux

If Ubuntu crashes into a busybox during the initramfs initialization, there may be a damaged superblock on the disk.

everal superblock copies are kept in Linux. To recover a system in case this problem occurs, you need to boot from the rescue image/disk/Live CD and run the terminal prompt. After booting, enter the following command in the terminal:

# sudo fdisk -l|grep Linux|grep -Ev 'swap'

The command returns the information about your volume:

/dev/vda2 4096 83884031 83879936 40G Linux filesystem

Remember the volume name and specify it in the following command:

# sudo dumpe2fs /dev/vda2 | grep superblock

The command will show the list of backup superblocks:

We will use the second backup superblock to replace the damaged one (you can use any superblock except Primary). Check the disk using the backup superblock:

# sudo fsck -b 98304 /dev/vda2 -y

fsck from util-linux 2.31.1
e2fsck 1.44.1 (24-Mar-2018)
/dev/vda2 is mounted.
e2fsck: Cannot continue, aborting

After successfully replacing the superblock, you will get a message like this:

fsck from util-linux 2.31.1
e2fsck 1.44.1 (24-Mar-2018)
/dev/vda2 was not cleanly unmounted, check forced.
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
Free blocks count wrong for group #231 (32254, counted=32253).
Fix? yes
Free blocks count wrong for group #352 (32254, counted=32248).
Fix? yes
Free blocks count wrong for group #358 (32254, counted=27774).
Fix? yes
..........
/dev/vda2: ***** FILE SYSTEM WAS MODIFIED *****
/dev/vda2: 85986/905464576 files (0.2% non-contiguous), 3904682/905464576 blocks

Then unmount the boot media and restart your computer. Everything should work properly.

Fsck Boot Error: Unexpected Inconsistency

The second variant of the initramfs (BusyBox) issue includes the following message in the terminal window:

/dev/sda1: UNEXPECTED INCONSISTENCY; RUN fsck MANUALLY
The root filesystem on /dev/sda1 requires a manual fsck.

The message will show a volume that that requires running a manual disk check. Run the following command in the initramfs prompt:
# fsck /dev/sda1 -y
After the disk check is over, restart your computer and make sure that Linux boots correctly.

Alert!? /dev/volume Does Not Exist

Fstab Issue

You can see the following error when booting the Linux host:

ALERT! /dev/sda1 does not exist. Dropping to a shell.

You may have just installed your Linux or your host has some fstab problems. The most often the problem occurs when a system is installed from a USB drive. The system may show an error of any volume. Like in the first case, we have to boot from the rescue/boor Linux media and do some actions. Check the disk UUID using this command:
# sudo blkid

The system will return something like this:

/dev/sda2: UUID="36cce3d5-cbdb-46f4-adbf-3f9aaa01d729" TYPE="ext4" PARTUUID="fea4dab1-4e12-4327-85c6-76ade18f64e1"

Here we see that the system must boot from sda2, but actually it tries to boot from sda1.

Mount the volume to any directory, for example:

# sudo mount /dev/sda2 /mnt