We are unable to update rpm's in one of the AIX server we are getting error like

error: rpmdb: Thread/process 11927852/1 failed: Thread died in Berkeley DB library
error: db4 error(-30974) from dbenv->failchk: DB_RUNRECOVERY: Fatal error, run database recovery
error: cannot open Packages index using db4 - (-30974)
error: cannot open Packages database in /opt/freeware/packages
error: rpmdb: Thread/process 11927852/1 failed: Thread died in Berkeley DB library
error: db4 error(-30974) from dbenv->failchk: DB_RUNRECOVERY: Fatal error, run database recovery
error: cannot open Packages index using db4 - (-30974)
error: cannot open Packages database in /opt/freeware/packages

Then we tried to rebuild the rpm with the below commands

645 cp -rp /opt/freeware/packages /opt/freeware/packages.bak
646 cd /opt/freeware/packages
647 rm -f __db.* Packages
648 rpm --rebuildb
649 which rpm
650 /usr/bin/rpm --rebuilddb
651 rpm -qa

After that we are unable to see any rpms when we execute rpm -qa.

One shouldn't be removing the Packages file, just removing __db.* file is enough to resolve the reported error.

Copy the Packages file from backup and retry again.