So I'm trying to update my CentOS EC2 instance on AWS and I'm getting the "Illegal Instruction" error. There's not much of any info around and related topics about "Illegal Instruction" does not fit on my problem. To be clear, here's what I see from the console.

yum -y update 
Loaded plugins: fastestmirror Setting up Update Process Loading mirror speeds from cached hostfile Illegal instruction

Luckily, there was a recent thread in CentOS Forum about the issue. It has something to do with AES. Apprently, there's some problem on CentOS 6.8 and is related to a bug. Just a couple of days ago, Redhat released a bug fix, RHBA-2016:1397 to resolve the problem.

Here's the explanation of the problem.

Previously, the Advanced Encryption Standard (AES) lacked a test to determine if the operating system (OS) supported Advanced Vector Extensions (AVX). As a consequence, segmentation faults occurred when certain applications used the libfreeblpriv3.so library after updating to Red Hat Enterprise Linux 6.8. With this update, libfreeblpriv3.so verifies if the OS supports AVX. As a result, segmentation faults no longer occur in the described scenario. (BZ#1337821)

Anyway, the temporary fix is to update a flag.

export NSS_DISABLE_HW_AES=1 yum -y update

The actual link to the topic is https://www.centos.org/forums/viewtopic.php?t=58002.

CentOS Bug tracker is in https://bugs.centos.org/view.php?id=10930&nbn=5.

Ciao!