ORA-21561: OID generation failed

when creating database with dbca, shown error : ORA-21561: OID generation failed.

SOLUTION:

problem is most likely machine hosts file. check if there is written host ip and hostname, if this is missing then write it.

with root user:

# vi /etc/hosts

machine_ip      hostname

re-run dbca and you will see that above error is disappeared.
that's all.