yum Error:rpmdb open failed

This is how I fixed my problem.

This is quite the messy situation. You may fix this by cleaning out rpm database. To minimize risk, make a backup of files in /var/lib/rpm/ using cp command:

mkdir /root/backups.rpm.mm_dd_yyyy/
cp -avr /var/lib/rpm/ /root/backups.rpm.mm_dd_yyyy/

To fix this problem, try:

# rm -f /var/lib/rpm/__db*
# db_verify /var/lib/rpm/Packages
# rpm --rebuilddb
# yum clean all

Verify that error has gone with the following yum command

# yum update -y