After an upgrade, grub2 can't find commands

[Jimmie Mayfield]

I upgraded my OpenSuSE 42.3 machine to OpenSuSE 15.0 today and it's 
resulted in a broken grub that's exhibiting behavior that I don't 
understand.  I'm trying to recover.

What happens is this:

Following a reboot, grub displays the boot menu like normal.  If I press 
<enter> to select the default entry (or let it time-out and 
auto-select), I see a brief message about loading initrd and then 
suddenly I go back to the grub menu.  This time, if I press <enter> on 
any entry, I get errors like "error: can't find command insmod" or 
"error: can't find command linux" or "error: can't find command echo".  
These errors appear to correspond to the commands in the default 
menuentry stanza.

If after a reboot I instead cursor to any other menu item (eg. don't 
just press <enter>), I'm immediately greeted by these "error: can't find 
command xxxxxx" errors.

If I enter a grub command line, and press <tab>, I see that the only 
available commands are:  ".", "[", "acpi", "all_functional_test", 
"authenticate", "background_color", and "backtrace".  Nothing else.  
With only these commands to work with, I don't think there's much that I 
can do from the command line to boot my kernel.

I've tried re-running grub-install from a rescue image to no avail.  The 
behavior remains.

Any clues what might cause grub to behave like this and how to recover?