Getting errors during boot process - 'No Media Present......System BootOrder not found. Initializing defaults.'

Issue

• While merging the snapshot lvm volume back to the root lv, and restoring the contents of /boot, /boot/efi partitions using steps in "How can I deploy a system and use LVM snapshot/merge to be able to restore an earlier state of the root filesystem?" in the subsequent reboot, system is unable to load GRUB menu and shows GRUB prompt:

  ...
  Minimal BASH-like line editing is supported. For the first word,
  TAB lists possible command completions. Anywhere else TAB lists
  possible device or file completions.
  ...
  grub> exit
  

  After exiting the GRUB prompt above, system shows below messages:

  >>Checking Media Presence......
  >>No Media Present......System BootOrder not found.  Initializing defaults.
  Creating boot entry "Boot0001" with label "Red Hat Enterprise Linux" for file "\EFI\redhat\shimx64.efi"
  
  ... (blank lines removed) ...
  ...
  Red Hat Enterprise Linux Server (3.10.0-514.el7.x86_64) 7.4 (Maipo)
  Red Hat Enterprise Linux Server (0-rescue-14e24d5d47ad40979127c9fd0c09c7>
  ...
  

  Although system is able to boot after above errors, what is the root cause for these errors and how to prevent the same?