Why does the ReaR backup fails with error "Cannot autodetect what is used as bootloader, see default.conf about 'BOOTLOADER'."

Issue

• Creating Rear backup fails with below error :

# rear -Dd mkbackup
Relax-and-Recover 2.4 / Git
Using log file: /var/log/rear/rear-xxx.log
Using UEFI Boot Loader for Linux (USING_UEFI_BOOTLOADER=1)
Creating disk layout
ERROR: Cannot autodetect what is used as bootloader, see default.conf about 'BOOTLOADER'
Aborting due to an error, check /var/log/rear/rear-xxx.log for details
Exiting rear mkbackup (PID 98756) and its descendant processes
Running exit tasks
You should also rm -Rf --one-file-system /tmp/rear.DwrQXdFSBnw1vaw
Terminated