attempt to load openSUSE installation kernel and initrd produces kernel has invalid signature

[Felix Miata <mrmazda@earthlink.net>]

Secure boot is not enabled in BIOS or any installation on this multiboot system.
Why would such a boot impediment and message be produced by Stretch's Grub?

If I instead try to chainload to the already installed openSUSE TW's Grub (on
EXT4 gpt6), I get only

	Booting a command list
	error: invalid sector size 65535".
	Press any key to continue...
 :-(
-- 
"Wisdom is supreme; therefore get wisdom. Whatever else you
get, get wisdom." Proverbs 4:7 (New Living Translation)

 Team OS/2 ** Reg. Linux User #211409 ** a11y rocks!

Felix Miata  ***  http://fm.no-ip.com/