Fix Kernel Panic: VFS Unable to Mount Root FS on unknown-block(0,0) in Ubuntu

After a routine kernel update on Ubuntu 24.04, my PC refused to boot and dropped straight into a kernel panic. Here is the exact error, the real cause, and the commands that fixed it.

The Error

KERNEL PANIC!
Please reboot your computer.
VFS: Unable to mount root fs on unknown-block(0,0)

What Causes It

unknown-block(0,0) means the kernel has no initramfs, so the storage driver needed to mount your root filesystem never loads.

In my case the kernel package installed fine, but the NVIDIA DKMS module failed to build against the new kernel. That failure killed the post-install script before update-initramfs ran — so /boot got a vmlinuz file with no matching initrd.img.

Other common causes: /boot partition full, or an interrupted apt upgrade.

Step 1: Boot Into the Old Kernel

At the boot screen, choose Advanced options for Ubuntu and select the previous kernel version. If the GRUB menu does not appear, hold Shift or tap Esc during startup.

Step 2: Confirm the Missing initramfs

df -h /boot
ls -l /boot/initrd.img-* /boot/vmlinuz-*

If a vmlinuz-<new-version> exists but the matching initrd.img-<new-version> is missing, that confirms the problem.

Step 3: Find the Real Failure

sudo dpkg --configure -a

This showed the actual error — the NVIDIA driver could not compile against the new kernel:

Autoinstall of module nvidia/580.126.20 for kernel 7.0.0-30-generic (x86_64)
Building module(s)......(bad exit status: 2)
Error! Bad return status for module build

Step 4: Make the System Bootable Immediately

You can generate the initramfs manually. This fixes the kernel panic even before the driver issue is solved.

sudo update-initramfs -c -k 7.0.0-30-generic
sudo update-grub
ls -lh /boot/initrd.img-7.0.0-30-generic

Replace 7.0.0-30-generic with your kernel version. The file should be around 70–80 MB. If -c says the file already exists, use -u instead.

Step 5: Install a Compatible NVIDIA Driver

Older driver branches do not build against newer kernels. Check what is available:

ubuntu-drivers list
lspci -nn | grep -i vga

• RTX 20xx / GTX 16xx or newer → use the -open variant
• GTX 10xx or older → use the standard proprietary package

sudo apt purge '^nvidia-.*580.*'
sudo apt install nvidia-driver-610-open

Step 6: Fix the “trying to overwrite” Error

The install may stop with a file conflict:

dpkg: error processing archive libnvidia-gl-610...
 trying to overwrite '/usr/lib/x86_64-linux-gnu/libnvidia-egl-xcb.so.1.0.5',
 which is also in package libnvidia-egl-xcb1

At this point apt refuses to run any command, including the purge that would fix it. Break the deadlock with dpkg directly:

cd /tmp
apt download libnvidia-gl-610
sudo dpkg -i --force-overwrite libnvidia-gl-610_*.deb
sudo apt -f install
sudo dpkg --configure -a

Or do it in one command:

sudo apt -o Dpkg::Options::="--force-overwrite" --fix-broken install

Note: Ignore any :i386 warnings. Those are recommendations, not dependencies, and are not the blocker.

Step 7: Rebuild and Verify

dkms status
sudo update-initramfs -u -k all
sudo update-grub
sudo apt autoremove --purge

dkms status should list the driver as installed for your new kernel.

Check Secure Boot First

mokutil --sb-state

If it returns disabled, reboot now. If enabled, enroll the signing key first or the modules will be rejected:

sudo mokutil --import /var/lib/shim-signed/mok/MOK.der

Set a one-time password and complete enrollment in the blue MOK Manager screen on next boot.

Step 8: Reboot and Confirm

sudo reboot

# after reboot
uname -r
nvidia-smi

The system now boots on the latest kernel with a working GPU driver.

If You Cannot Boot Any Kernel

Use a live USB and chroot into your installation:

lsblk
sudo mount /dev/nvme0n1p2 /mnt
sudo mount /dev/nvme0n1p1 /mnt/boot/efi
for d in dev proc sys run; do sudo mount --bind /$d /mnt/$d; done
sudo chroot /mnt
update-initramfs -c -k all && update-grub

Adjust the partition names to match your lsblk output.

Quick Summary

1. Boot the old kernel from GRUB → Advanced options
2. Run sudo dpkg --configure -a to find the real error
3. Run sudo update-initramfs -c -k <version> and sudo update-grub
4. Install a driver version that supports your kernel
5. Clear package conflicts with --force-overwrite
6. Reboot

FAQ

Will I lose my data?

No. This is a boot-time driver problem. Your files are untouched.

Can I just delete the new kernel instead?

Yes, sudo apt purge linux-image-<version> works as a temporary fix, but the same failure returns on the next kernel update unless you fix the driver.

Does this apply to AMD or Intel graphics?

The initramfs fix in Steps 1–4 applies to any system. Steps 5–6 are NVIDIA specific. On AMD or Intel, a full /boot partition is the more likely cause.