Failed upgrade from Ubuntu 19.10 to 20.04 "Please update the microcode"

While installing the Ubuntu 20.04 updates during upgrade from 19.10 to 20.04, my screen suddenly went completely white and displayed a message saying

Please logout and try again.

But I could not locate my cursor and so I switched off my laptop. After restarting it again, it was showing an error message saying

Please update the microcode

Why did this happen? How can I solve this problem?

You still can try to fix this interrupted upgrade from a live USB/CD.

To fix from a live USB/CD, boot into the live system then connect to Internet from the live system and open a terminal then follow these steps:

Run:

sudo fdisk -l

And identify your root partition. It could be something like /dev/sda1 then mount it to /mnt like so:

sudo mount /dev/sda1 /mnt/

Then run:

sudo mount --bind /proc/ /mnt/proc/

Then run:

sudo mount --bind /sys/ /mnt/sys/

Then run:

sudo mount --bind /dev/ /mnt/dev/

Then run:

sudo cp /etc/resolv.conf /mnt/etc/resolv.conf

Then run:

sudo chroot /mnt/

Now you are in your original system on the hard disk. Run first:

sudo dpkg --configure -a

Then, update APT like so:

sudo apt update

Then, install upgrades like so:

sudo apt upgrade

When finished run:

exit

Then run:

sudo umount /mnt/dev/

Then run:

sudo umount /mnt/sys/

Then run:

sudo umount /mnt/proc/

Then run:

sudo umount /mnt/

Then reboot to your original system, it should be fixed