How to solve dsconf error - Backend userroot: can't open LDIF: 13 (Permission denied) while running as user "dirsrv"

Issue

While exporting a database in Red Hat Directory Server to custom location backup_dir with a custom name backup_file_name.ldif , it returns error:

# dsconf -D "cn=Directory Manager" -w password ldap://ldapserver.example.com backend export -l backup_dir/backup_file_name.ldif userroot
Error: Export task failed
-------------------------
Beginning export of 'userroot'
Backend userroot: can't open backup_dir/backup_file_name.ldif: 13 (Permission denied) while running as user "dirsrv"
backend 'userroot' export failed (-1)
Export failed.