[CentOS] 8.2.2004 Latest yum update renders machine unbootable

Sat Aug 1 03:20:28 UTC 2020
Johnny Hughes <johnny at centos.org>

On 7/31/20 11:24 AM, Alessandro Baggi wrote:
> Il 31/07/20 13:08, ja ha scritto:
>> On Fri, 2020-07-31 at 22:35 +1200, Alan McRae via CentOS wrote:
>>> I am running an Intel x64 machine using UEFI to boot an SSD.
>>> Installing the latest yum update which includes grub2 and kernel
>>> 4.18.0-193.14.2.el8_2.x86_64 renders the machine unbootable, blank
>>> screen where grub should be, no error messages, just hangs.
>>> After some hours I managed to modify another bootable partition
>>> (containing older software) and boot it from there.
>>> After that, I  found out it is a known problem.
>>> The main point of this message is to make people aware of the problem
>>> and suggest admins don't run 'yum update' until they understand the
>>> problem and have a fix at hand.
>>> See 'UEFI boot blank screen post update' for a solution and directions
>>> to the redhat article.
>>> Regards
>>> Alan
>> I have been punished by this bug - it is/was very nasty.
> Me too. Luckily it happened on a test machine.
> Sorry but seems that those packages were not tested before pushing them
> in the update repo. Would be great to know what happened to the
> mainstream chains and how a package like grub reached the update repo
> when it has serious problem (genuine curiosity but not to blame them).

Of course it was tested before it was pushed. Obviously this is not a
problem with every install.  Surely you don't think we push items
without doing any testing.  Certainly not items as important as this update.

 The CentOS infrastructure has hundreds of servers, most of them were
not impacted (as an example). In fact, we seem to have had this happen
on only one machine in those hundreds so far.  It is a problem, obviously.

The issue seems to be with the shim package (not the grub or kernel
packages) and we are currently working with Red Hat on a fix.  This
issue happened in many Linux OSes and even Windows, not just RHEL and

We will push a fix as soon as one is available.

I would hold off on installing this until we release the new fixes.

> In my case, the restore procedure reported by RH in case of reboot does
> not work and reports that the packages are already at the lowest version
> and that the downgrade is not possibile. I don't know why.

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