Fixing KERNEL PANIC! VFS: Unable to mount fs on unknown-block(0,0)

I had this on an Ubuntu 24.04 LTS which had updated the kernel. The problem is that there is no initramfs for the kernel version you are trying to boot.

• Boot on a USB-stick with a live image of Ubuntu, using the Try Ubuntu boot option
• List the devices in the system:
  sudo fdisk -l
• Your disk is probably something like /dev/sda1 or /dev/sda2. In my case it was /dev/sda2. Do:
  sudo mount /dev/sda2 /mnt
sudo mount --bind /dev /mnt/dev
sudo mount --bind /dev/pts /mnt/dev/pts
sudo mount --bind /proc /mnt/proc
sudo mount --bind /sys /mnt/sys
sudo chroot /mnt
• List the kernels installed:
  dpkg --list | grep linux-image
• Generate initramfs for the latest version, in my case 6.17.0-14-generic:
  update-initramfs -u -k 6.17.0-14-generic
• Update grub:
  update-grub
• Shutdown, remove the live USB-stick and restart the computer.