You can see below is the error while updating RHEL/CentOS/Fedora using yum update
[root@babar rpm]# yum update
rpmdb: Thread/process 8367/457660786 failed: Thread died in Berkeley DB library
error: db4 error(-41638) from dbenv->failchk: DB_RUNRECOVERY: Fatal error, run database recovery
error: cannot open Packages index using db3 – (-30575)
error: cannot open Packages database in /var/lib/rpm
CRITICAL:yum.main:Error: rpmdb open failed
New Please check RPMDB file and rebuild if corrupted using below commands