Research shibboleth.net failure to boot without intervention

This was resolved by moving from CentOS to a Rocky instance.

I do see now the issue with the rescue entry, I didn't pick up on the missing path prefix before. I just corrected that, as well as setting 0 to be default boot choice.

I did not change the GRUB_ENABLE_BLSCFG setting to false, though that's mentioned by a commenter on that article as something that apparently helped Fedora.

Until we reboot again, I doubt there's much more to do.

This link has been the most helpful so far :

https://www.linode.com/community/questions/19397/i-just-upgraded-my-centos-8-linode-and-now-it-wont-boot-how-do-i-fix-this-proble