How to re-generate the grubenv file if missing or corrupted ?

Environment

• Red Hat Enterprise Linux 7
• Red Hat Enterprise Linux 8

Issue

• The grubenv file is corrupted or missing in BIOS and UEFI systems.

• Detected a corrupted grubenv file in the /var/log/leapp/leapp-report.txt.

• Following messages were repeatedly observed in the /var/log/messages:

  grub2-set-bootflag[736726]: Error reading from /boot/grub2/grubenv: Invalid argument
  systemd[732552]: grub-boot-success.service: Main process exited, code=exited, status=1/FAILURE
  systemd[732552]: grub-boot-success.service: Failed with result 'exit-code'.
  systemd[732552]: Failed to start Mark boot as successful.
  

Resolution

• check the size of grubenv file , this should be 1024 in size , else the file is corrupted.

     For BIOS 
     # ls -l /boot/grub2/grubenv
  
     For UEFI
     # ls -l /boot/efi/EFI/redhat/grubenv
  

• Remove the corrupted remove grubenv file.

     For BIOS 
     # rm  /boot/grub2/grubenv
  
     For UEFI
     # rm /boot/efi/EFI/redhat/grubenv
  

• Re-generate the grubenv file.

  # grub2-mkconfig
  

Root Cause

• The leapp-report.txt had a inhibitor of missing files.

  Risk Factor: high (inhibitor)
  Title: Detected a corrupted grubenv file
  Summary: The grubenv file must be valid to pass the upgrade correctly: 
   - an exact size of 1024 bytes is expected 
   - it cannot end with a newline. 
  The corruption could be caused by a manual modification of the file which is not
   recommended.
  

Diagnostic Steps

• For a UEFI system the grubenv file was 953 in size which should be 1024.

  -rwx------. 1 root root 953 Apr 21  2023 /boot/efi/EFI/redhat/grubenv
  

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