Why server is booting into grub rescue> prompt with error "symbol grub_calloc not found" ?

Issue

• After rebooting the system, its getting stuck in grub rescue mode:

  symbol grub_calloc  not found
  Entering rescue mode
  grub rescue>
  

• GRUB cannot be installed on /dev/sda2 because it contains an XFS filesystem, which does not support embedding GRUB:

  grub2-install: warning: File system xfs' doesn't support embedding.
  grub2-install: warning: Embedding is not possible.  GRUB can only be installed                         in this setup by using blocklists.  However, blocklists are UNRELIABLE and their     use is discouraged..
  grub2-install: error: will not proceed with blocklists.