1.修改配置檔案：進入/etc/mysql/mysql.conf.d/ ，在配置檔案mysqld.cnf下新增skip-grant-tables

2.在終端輸入命令：sudo service mysql restart來重新啟動mysql服務

3.輸入:mysql -u root -p，回車進入mysql（此時不需要密碼即可直接進入）

4.輸入：use mysql；

5.輸入:update user set authentication_string='' where user='root';,將authentication_string 置空;

6.輸入：alter user 'root'@'localhost' identified by 'newpassword'；，newpassword為要修改的新密碼；

此時提示錯誤：ERROR 1290 (HY000): The MySQL server is running with the --skip-grant-tables option so it cannot execute this statement

輸入：FLUSH PRIVILEGES;

再重新alter user 'root'@'localhost' identified by 'newpassword'；

此時錯誤提示為：ERROR 1524 (HY000): Plugin 'auth_socket' is not loaded

，

輸入select user,plugin from mysql.user;來檢視plugin

這裡輸入update user set plugin='mysql_native_password' where user='root';將plugin改為以前版本的密碼認證方式

然後輸入：FLUSH PRIVILEGES;

再重試alter user 'root'@'localhost' identified by 'newpassword'；即可修改密碼

7.修改完成後輸入FLUSH PRIVILEGES;

8. 將第一步的skip-grant-tables註釋掉；

9.輸入service mysql restart重啟mysql