Error: Rpmdb changed underneath us

Problem:

Ran into this error while attempting to apply a yum update on a CentOS 6 machine to update its kernel packages.

Error: Rpmdb changed underneath us 

The same scenario applies if you get this error as well:

error: can not open Packages database in /var/lib/rpm

Cause:

The problem has to do with corruption in the RPM database files under the /var/lib/rpm directory.

Solution:

• Check for any processes that might be currently running and having a lock on the rpm database and kill them if they exist:
• ps -aufx | grep /var/lib/rpm
• Delete the temporary DB files:
• rm -fv /var/lib/rpm/__*\
• Rebuild your server RPM database using the below command:
• rpm --rebuilddb -v -v

After completing these steps, attempt to run a "yum update" again and it most likely would work fine now. 

It worked for me.

Original Solution Post:

https://www.eukhost.com/forums/forum/technical-support/tutorials-how-tos/18431-how-to-resolve-rpmdb-error-while-update-the-yum-on-server