Navicat 连接MySQL数据库出现错误：

2059-Authentication plugin'caching_sha2_password' cannot be loaded: （乱码）

错误原因：MySQL新版本（8以上版本）的用户登录账户加密方式是【caching_sha2_password】，Navicat不支持这种用户登录账户加密方式。

解决方式：

1. 进入mysql 命令界面：

show variables like 'default_authentication_plugin';

会出现：

+-------------------------------+-----------------------+
| Variable_name | Value |
+-------------------------------+-----------------------+
| default_authentication_plugin | caching_sha2_password |
+-------------------------------+-----------------------+
1 row in set (0.02 sec)

mysql> select host,user,plugin from mysql.user;
+-----------+------------------+-----------------------+
| host | user | plugin |
+-----------+------------------+-----------------------+
| % | root | caching_sha2_password |
| localhost | mysql.infoschema | caching_sha2_password |
| localhost | mysql.session | caching_sha2_password |
| localhost | mysql.sys | caching_sha2_password |
+-----------+------------------+-----------------------+

2. 修改root 用户 加密方式

ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY '123456';