Yum update problems on AWS with missing requirements and duplicate sendmail

Christian asked:

I am running an AWS VM and tried:

sudo yum update


Error: Protected multilib versions: sendmail-8.14.4-8.12.amzn1.x86_64 != sendmail-8.14.4-7.9.amzn1.i386
 You could try using --skip-broken to work around the problem
** Found 2 pre-existing rpmdb problem(s), 'yum check' output follows:
kernel- has missing requires of mkinitrd
sendmail-8.14.4-8.11.amzn1.x86_64 is a duplicate with sendmail-8.14.4-7.9.amzn1.i386

I read else where to try this:

sudo yum --exclude=kernel* update

But same result.

This is a production server which I want to upgrade so I have to take special care. I was not the one preparing it. Looks like I use the amazon version of Red Hat 4.4.6-3.

Any suggestions how to fix this?

My answer:

Use yum distro-sync instead of yum update to fix package version mismatches in this scenario. This allows for packages to be downgraded if necessary to match the versions in the repositories.

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