MySQL 8.0报错：error 2059: Authentication plugin 'caching_sha2_password' cannot be loaded

报错信息：

error 2059: Authentication plugin 'caching_sha2_password' cannot be loaded: /usr/lib64/mysql/plugin/caching_sha2_password.so: cannot open shared object file: No such file or directory

运行环境：centos7.4 +MySQL 8.0.11

mysql> select version();
+-----------+
| version() |
+-----------+
| 8.0.11    |
+-----------+
1 row in set (0.00 sec)

mysql> show variables like 'default_authentication_plugin';
+-------------------------------+-----------------------+
| Variable_name                 | Value                 |
+-------------------------------+-----------------------+
| default_authentication_plugin | caching_sha2_password |
+-------------------------------+-----------------------+
1 row in set (0.01 sec)

mysql> select host,user,plugin from mysql.user;
+-----------+------------------+-----------------------+
| host      | user             | plugin                |
+-----------+------------------+-----------------------+
| %         | root             | caching_sha2_password |
| localhost | mysql.infoschema | mysql_native_password |
| localhost | mysql.session    | mysql_native_password |
| localhost | mysql.sys        | mysql_native_password |
| localhost | root             | caching_sha2_password |
+-----------+------------------+-----------------------+
5 rows in set (0.00 sec)

MySQL5.7版本：

mysql> select version();
+------------+
| version()  |
+------------+
| 5.7.15-log |
+------------+
1 row in set (0.00 sec)

mysql> show variables like 'default_authentication_plugin';
+-------------------------------+-----------------------+
| Variable_name                 | Value                 |
+-------------------------------+-----------------------+
| default_authentication_plugin | mysql_native_password |
+-------------------------------+-----------------------+
1 row in set (0.01 sec)

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

可以看到MySQL8.0.11版本默认的认证方式是caching_sha2_password ，而在MySQL5.7版本则为mysql_native_password。

若想在MySQL8.0版本中继续使用旧版本中的认证方式需要在my.cnf 文件中配置并重启，因为此参数不可动态修改。

mysql> set global default_authentication_plugin='mysql_native_password';
ERROR 1238 (HY000): Variable 'default_authentication_plugin' is a read only variable

写入my.cnf 文件后重启MySQL：

vim my.cnf
[mysqld]
default_authentication_plugin=mysql_native_password

第二种解决方法：兼容新老版本的认证方式。

ALTER USER 'root'@'localhost' IDENTIFIED BY 'root' PASSWORD EXPIRE NEVER; #修改加密规则 
ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY 'root'; #更新一下用户的密码 
FLUSH PRIVILEGES; #刷新权限
	--创建新的用户：
	create user root@'%' identified WITH mysql_native_password BY 'root';
	grant all privileges on *.* to root@'%' with grant option;
	flush privileges;
	--在MySQL8.0创建用户并授权的语句则不被支持：
	mysql> grant all privileges on *.* to root@'%' identified by 'root' with grant option;
        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
        mysql>