$ mysql -u root

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

mysql> SELECT user,host,plugin FROM mysql.user;
+------------------+-----------+-----------------------+
| user             | host      | plugin                |
+------------------+-----------+-----------------------+
| mysql.infoschema | localhost | caching_sha2_password |
| mysql.session    | localhost | caching_sha2_password |
| mysql.sys        | localhost | caching_sha2_password |
| root             | localhost | mysql_native_password |
+------------------+-----------+-----------------------+
4 rows in set (0.01 sec)

$ mysql --help | grep my.cnf
                      order of preference, my.cnf, $MYSQL_TCP_PORT,
/etc/my.cnf /etc/mysql/my.cnf /usr/local/etc/my.cnf ~/.my.cnf

# Default Homebrew MySQL server config
[mysqld]
# Only allow connections from localhost
bind-address = 127.0.0.1
# 追加
default_authentication_plugin=mysql_native_password

$ mysql.server stop

$ launchctl unload ~/Library/LaunchAgents/homebrew.mxcl.mysql.plist

$ mysql.server status
 ERROR! MySQL is not running

$ launchctl unload ~/Library/LaunchAgents/homebrew.mxcl.mysql.plist

  #ps:如果命令报错，不用管，直接执行  mysql.server start

$ mysql.server status
 SUCCESS! MySQL running (XXXXX)