GRUB Error: "Disk filter writes are not supported in boot"

UCS 4.1 Erratum 82 and UCS 4.0 Erratum 396 added/activated the “savedefault” option by default. This requires GRUB to write to the disk, which is not supported for every type of device (e.g. mdadm-software-RAID)

If GRUB can not write to the disk it displays the message

“Disk filter writes are not supported in boot”

and requires a key press to continue the boot.

As the function does not work if GRUB can not write, the “savedefault” option can be disabled by executing the following command:

ucr set grub/savedefault=false