Fixing Linux Boot Failure Due to fstab Mount Errors

If you’ve edited /etc/fstab incorrectly or a disk UUID has changed, Linux may fail to mount a filesystem during boot — leaving you stuck at an emergency shell or a completely unbootable system. Here’s how to fix it.

The Problem

When Linux boots, it reads /etc/fstab to mount filesystems. If an entry is invalid (wrong UUID, missing disk, syntax error), you’ll see something like:

A start job is running for /dev/disk/by-uuid/xxxx (1min 30s / 1min 30s)
[FAILED] Failed to mount /mnt/data.
[DEPEND] Dependency failed for Local File Systems.
You are in emergency mode. After logging in, type "journalctl -xb" to view system logs...

Give root password for maintenance
(or press Control-D to continue):

At this point, your system won’t boot normally.

Solution: Boot into a Root Shell via GRUB

Step 1: Access GRUB menu

When your computer starts, hold Shift (or Esc on some systems) to access the GRUB boot menu.

Step 2: Edit boot parameters

1. Highlight Ubuntu (or your Linux entry)
2. Press e to edit

Step 3: Modify the boot line

Find the line starting with:

linux /boot/vmlinuz-...

Replace:

ro quiet splash

with:

rw init=/bin/bash

(Or append rw init=/bin/bash at the end of that line)

Step 4: Boot

Press Ctrl + X to boot with the modified parameters.

Step 5: Edit fstab

You’ll be dropped into a root shell with the filesystem mounted read-write. Now edit fstab:

nano /etc/fstab

Find the problematic line and either:

• Fix the UUID — use blkid to find the correct UUID
• Comment it out — add # at the beginning of the line
• Add nofail — append nofail to the options so boot continues even if mount fails

Example of adding nofail:

UUID=xxxx-xxxx  /mnt/data  ext4  defaults,nofail  0  2

Step 6: Reboot

exec /sbin/init

Or force a reboot:

reboot -f

Done! Hopefully this saves you from a headache next time your Linux system refuses to boot.