[CentOS] 8.2.2004 Latest yum update renders machine unbootable

Sat Aug 1 20:03:20 UTC 2020
Greg Bailey <gbailey at lxpro.com>

On 8/1/20 6:56 AM, david wrote:
> At 02:54 AM 8/1/2020, Alessandro Baggi wrote:
>> Hi Johnny,
>> thank you very much for clarification.
>> You said that in the centos infrastructure only one server got the 
>> problem.
>> What are the conditions that permit the breakage? There is a particular
>> configuration (hw/sw) case that match always the problem or it is 
>> random?
>> Thank you
> I have two servers running Centos 7 on apple hardware (one mac-mini 
> and one mac server).  They both failed to reboot a few days ago.  So 
> perhaps whatever anti-boot bug hit Centos 8, also hit Centos 7.  I 
> can't tell what version got updated since the system simply fails to 
> boot.  I don't even get a grub screen. I'll have to rebuild the 
> systems from scratch.

You should be able to boot off of installation media into rescue mode, 
and downgrade the grub2* and/or shim* RPMs.