ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'identified by 'root' with grant option' at line 1

mysql8中已经不支持grant all privileges on *.* to 'root'@'%' identified by '密码' with grant option这种写法。

应该使用

grant all privileges on *.* to 'root'@'%' ;