grub works, but boot menu is gone and has an error message. [corrected]

[John Griessen]

I've had this symptom for a while and cannot find much by searching for the 
error message.

During boot, when the grub menu usually would come up, I see

error: can't find command 'exec' .
loading 5.11.0-46-lowlatency
loading initramfs


I think I got this when updating and deleting and reinstalling low level ubuntu 
parts like busybox, syslinux, bash.

Any ideas what could be missing on my ubuntu 20.04 distro?
Ordinary running of grub-install /dev/sda  says good and doesn't change the 
symptom.

ll /sys/firmware/efi
ls: cannot access '/sys/firmware/efi': No such file or directory


sudo gdisk -l /dev/sda
[sudo] password for john:
GPT fdisk (gdisk) version 1.0.5

Partition table scan:
  MBR: MBR only
  BSD: not present
  APM: not present
  GPT: not present


***************************************************************
Found invalid GPT and valid MBR; converting MBR to GPT format
in memory.
***************************************************************

Disk /dev/sda: 500118192 sectors, 238.5 GiB
Model: INTEL SSDSCKKF25
Sector size (logical/physical): 512/512 bytes
Disk identifier (GUID): 2178828C-D2B9-4B38-BA80-294C83D53164
Partition table holds up to 128 entries
Main partition table begins at sector 2 and ends at sector 33
First usable sector is 34, last usable sector is 500118158
Partitions will be aligned on 2048-sector boundaries
Total free space is 19053 sectors (9.3 MiB)

Number  Start (sector)    End (sector)  Size       Code  Name
   1            2048         1050623   512.0 MiB   0700  Microsoft basic data
   5         1052672       475541503   226.3 GiB   8300  Linux filesystem
   6       475543552       500105215   11.7 GiB    8200  Linux swap


Thanks,
--
John