sudo dpkg-reconfigure grub-pc
Generating grub configuration file ...
  /dev/sda: open failed: No medium found
  /dev/sda: open failed: No medium found
  /dev/sda: open failed: No medium found
  /dev/sda: open failed: No medium found
  /dev/sda: open failed: No medium found
  /dev/sda: open failed: No medium found
  /dev/sda: open failed: No medium found
  /dev/sda: open failed: No medium found
  /dev/sda: open failed: No medium found
  /dev/sda: open failed: No medium found
  /dev/sda: open failed: No medium found
  /dev/sda: open failed: No medium found
  /dev/sda: open failed: No medium found
  /dev/sda: open failed: No medium found
  /dev/sda: open failed: No medium found
  /dev/sda: open failed: No medium found
Found background image: /usr/share/images/desktop-base/desktop-grub.png
  /dev/sda: open failed: No medium found
  /dev/sda: open failed: No medium found
Found linux image: /boot/vmlinuz-4.19.0-18-amd64
Found initrd image: /boot/initrd.img-4.19.0-18-amd64
Found linux image: /boot/vmlinuz-4.19.0-17-amd64
Found initrd image: /boot/initrd.img-4.19.0-17-amd64
  /dev/sda: open failed: No medium found
  /dev/sda: open failed: No medium found
  /dev/sda: open failed: No medium found
Adding boot menu entry for EFI firmware configuration
done