Pop!_OS / Ubuntu Drops to BusyBox (initramfs)

Fixing “Filesystem needs manual fsck”

This guide applies to:

Pop!_OS
Ubuntu
Debian-based systems
ext4 filesystems

What You’ll See

Instead of booting normally, the system drops to:

BusyBox v1.30.1 built-in shell (initramfs)
(initramfs)

You cannot log in normally.

This usually means:

The root filesystem is marked dirty
ext4 detected journal inconsistency
System refuses to mount root for safety

Do not panic. This is recoverable.

Step 1 – Check If Drive Is Detected

At the (initramfs) prompt:

ls /dev

Look for something like:

sda1
sda2
sda3

nvme0n1p1
nvme0n1p2

If you see your disk → good. Continue.

If you do NOT see your disk → possible hardware issue.

Step 2 – Identify the Root Partition

Try:

blkid

Look for the partition that says:

TYPE="ext4"

Example:

/dev/sda3: UUID="xxxx" TYPE="ext4"

That is likely your root partition.

If unsure, on most Pop!_OS installs:

sda1 = EFI
sda2 = recovery
sda3 = root

So try sda3 first.

Step 3 – Run Filesystem Repair

Run:

fsck -f -y /dev/sda3

Replace sda3 with your actual root partition if different.

Explanation of flags:

-f → force check even if marked clean
-y → automatically answer “yes” to repair prompts

Let it complete.

You may see:

Journal recovery
Inode fixes
Orphaned block cleanup

This is normal.

Step 4 – Reboot

When fsck finishes:

reboot -f

System should boot normally.

Why This Happens

Even if you shut down via GUI, a dirty journal can happen due to:

Interrupted shutdown
Power instability
Disk I/O delay
Kernel update edge case
Rare transient disk error

ext4 refuses to mount to prevent corruption.

It is protecting your data.

After Booting Normally (Recommended)

Check disk health:

sudo apt install smartmontools
sudo smartctl -a /dev/sda

Look for:

SMART overall-health self-assessment test result: PASSED

And verify these are zero:

Reallocated_Sector_Ct
Current_Pending_Sector
Offline_Uncorrectable

If all clean → likely just a one-time dirty shutdown.

When To Worry

Investigate further if:

This happens repeatedly
SMART shows sector errors
System freezes often
Disk disappears from BIOS

Otherwise, a single event is not alarming.

Mental Model

ext4 detected inconsistency → refused to mount → initramfs dropped to BusyBox → fsck repaired journal → filesystem marked clean → boot proceeds

That is normal Linux safety behavior.

Fixing “Filesystem needs manual fsck”​

What You’ll See​