[CentOS-devel] recent updates cause grub not to load please advise

On Thu, 30 Jul 2020 Sandro Bonazzola wrote...

>I think you can follow here: Bug 1861977
>https://bugzilla.redhat.com/show_bug.cgi?id=1861977 - RHSA-2020:3216
>grub2 security update renders system unbootable

Thanks very much...I can confirm the following does work...

1) booting to rhel-8 (centos-8) troubleshooting mode from a boot CD / USB
2) chrooted to /mnt/sysimage
3) setup networking
4) yum downgrade shim-x64 grub2\*
5) add exclude=grub2* shim* to /etc/yum.conf
6) reboot

N.B. If you are on CentOS-stream then the repos will NOT have the
older packages so just point to the CentOS repo ( or download from
that repo and rpm -Uvh --force to install them )