密码字节数的问题，设置 old_passwords=0 即可解决；

在 mysql的my.ini文件中将old_passwords=1 修改为 0；

或者 set old_passwords =0;

一、修改以前的：

mysql> SELECT user, Length(`Password`) FROM `mysql`.`user`;  +------+--------------------+ | user | Length(`Password`) | +------+--------------------+ | root |                 16 | | root |                  0 | |      |                  0 | | test |                 16 | | test |                 16 | +------+--------------------+ 5 rows in set

二、修改 old_passwords;

mysql> set old_passwords=0; Query OK, 0 rows affected

三、修改用户:

mysql> UPDATE mysql.user SET Password = PASSWORD( ') WHERE user = 'root '; Query OK, 2 rows affected Rows matched: 2  Changed: 2  Warnings: 0 Query OK, 0 rows affected

四、查看：

SELECT user, Length(`Password`) FROM `mysql`.`user`;  +------+--------------------+ | user | Length(`Password`) | +------+--------------------+ | root |                 41 | | root |                 41 | |      |                  0 | | test |                 16 | | test |                 16 | +------+--------------------+ 5 rows in set

 

可以看到已经更新成功了，将其他用户都更新了即可。