root创建用户失败提示:Access denied; you need (at least one of) the (GRANT) privilege(s) for this operation

version :3.1.3 (2.1.10 -> 3.0 ->3.1.3)

sql :CREATE USER 'username'@'%' IDENTIFIED BY 'xxx';

错误提示 : errCode = 2, detailMessage = Access denied; you need (at least one of) the (GRANT) privilege(s) for this operation