mysqlnd cannot connect to MySQL 4.1+ using the old insecure authentication

升级PHP,数据库报错

mysqlnd cannot connect to MySQL 4.1+ using the old insecure authentication. Please use an administration tool to reset your password with the command SET PASSWORD = PASSWORD('your_existing_password'). This will store a new, and more secure, hash value in mysql.user. If this user is used in other scripts executed by PHP 5.2 or earlier you might need to remove the old-passwords flag from your my.cnf file

重置一下密码就好了

SET old_passwords = 0;
UPDATE mysql.user SET PASSWORD = PASSWORD( '123456' ) WHERE User = 'root';
FLUSH PRIVILEGES ;