Ubuntu Boot on device fails with 'kernel panic'

Introduction

Problem description

Ubuntu Boot fails with the following message:

[ 0.52] Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)
[ 0.52] CPU: 2 PID: 1 COMM: swapper/0 Not tainted 5.4.0.67.generic #75~18.04.1.Ubuntu
...

This is because the Ubuntu package update was interrupted (eg. by a power outage), and the newest Ubuntu kernel package was corrupted or unsigned and therefore cannot boot correctly.

Scope

Solution applies to: NavVis VLX and NavVis M6

Troubleshooting procedure

1. Connect a cable-bound keyboard to the device.

2. During boot the Intel NUC screen is shown on the display. Press F10 to enter the GRUB Boot Menu

   

3. The GRUB menu shows up, navigate with the keyboard arrows to Advanced Options for Ubuntu and press ENTER.

   

4. The bootable kernel list shows up. The one on top should be the newest and, therefore, the corrupted one. Navigate with the keyboard arrows to an older one further below with NO "recovery mode" label and press ENTER.

5. The IMMS should boot now normally on an older kernel.

   This is a help question in the Ubuntu forums targeting the problem:  https://askubuntu.com/questions/41930/kernel-panic-not-syncing-vfs-unable-to-mount-root-fs-on-unknown-block0-0

6. Open a terminal and run the following commands.

   sudo dpkg --configure -a
   
   dpkg --list | grep linux-image #to find your newest kernel version
   update-initramfs -u -k 2.6.38-8-generic #or your version
   sudo update-grub2
   
   sudo apt-get update
   sudo apt-get dist-upgrade
   sudo apt-get autoremove

7. Restart the IMMS and see if it starts normally.