OPW-00029: Password complexity failed for SYS user : Password must contain at least 8 characters.

Problem : 

creating password file with password less then 8 character gives error on 12.2 database

-bash-4.2$ orapwd file=orapwabc password=dbpwd entries=5

OPW-00029: Password complexity failed for SYS user : Password must contain at least 8 characters.

Solution:

create password in 12.1 format