FAIL Execute SQL / return code: 256

hi guys I'm optimizing mysql with "perl /sbin/mysqltuner.pl" when executing this script, it generates an alert message [!!] FAIL Execute SQL / return code: 256 [!!] failed to execute: SELECT CONCAT(user, '@', host) FROM mysql.user WHERE IF(plugin='mysql_native_password', authentication_string, password) = PASSWORD('freddy') OR IF(plugin='mysql_native_password', authentication_string, password) = PASSWORD(UPPER('freddy')) OR IF(plugin='mysql_native_password', authentication_string, password) = PASSWORD(CONCAT(UPPER(LEFT('freddy', 1)), SUBSTRING('freddy', 2, LENGTH('freddy')))) [!!] FAIL Execute SQL / return code: 256 [!!] failed to execute: SELECT CONCAT(user, '@', host) FROM mysql.user WHERE IF(plugin='mysql_native_password', authentication_string, password) = PASSWORD('maxwell') OR IF(plugin='mysql_native_password', authentication_string, password) = PASSWORD(UPPER('maxwell')) OR IF(plugin='mysql_native_password', authentication_string, password) = PASSWORD(CONCAT(UPPER(LEFT('maxwell', 1)), SUBSTRING('maxwell', 2, LENGTH('maxwell')))) How can this error message be fixed?