I'm getting the errors
Could not create MOKlistXRT: Out of resources
and
something has gone seriously wrong: import_MOK_state(): Out of resources
when trying to boot 21.04 clean installed from a flash drive onto a Dell Latitude E6410 laptop with A17 BIOS in UEFI mode.
I saw the similar previous post referring to "18.04 UEFI boot fails" and tried the solution given there, but in my Latitude's A17 UEFI settings, "General > Boot Sequence > Add Boot Option > File System List" only shows the EFI and msdata partitions with no filenames visible.
There's no way to browse for grubx64.efi as suggested there. Entering EFI/ubuntu/grubx64.efi under "File Name" doesn't help. I've verified that the file is present at that location.