今天下了个 MySQL8.0，发现Navicat连接不上，总是报错1251；

原因是MySQL8.0版本的加密方式和MySQL5.0的不一样，连接会报错。

更改加密方式

1.先通过命令行进入mysql的root账户：(一般是在C:\Program Files\MySQL\MySQL Server 8.0\bin
执行cmd)

C:\Windows\system32> mysql -uroot -p

再输入root的密码：

Enter password: ******

Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 18
Server version: 8.0.11 MySQL Community Server - GPL
Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql>

2.更改加密方式：

mysql> ALTER USER 'root'@'localhost' IDENTIFIED BY 'password' PASSWORD EXPIRE NEVER;

Query OK, 0 rows affected (0.10 sec)

 3.更改密码：

mysql> ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY 'password';

Query OK, 0 rows affected (0.35 sec)

4.刷新：

mysql> FLUSH PRIVILEGES;

Query OK, 0 rows affected (0.28 sec)

// 如果报错   ERROR 1396 (HY000): Operation ALTER USER failed for 'root'@'%' ：

则是远程访问权限不正确，先选择数据库，查看一下再更改：

mysql> use mysql;
Database changed
mysql> select user,host from user;
+------------------+-----------+
| user             | host      |
+------------------+-----------+
| mysql.infoschema | localhost |
| mysql.session    | localhost |
| mysql.sys        | localhost |
| root             | localhost |
+------------------+-----------+
5 rows in set (0.00 sec)