Can not reload FreePBX due to 255 error (Exec(): Null byte detected)

After reboot the server, i suddenly encouter this error while applying new config for Freepbx:
Reload failed because retrieve_conf encountered an error: 255
exit: 255
Unable to continue. exec(): NULL byte detected. Possible attack in /var/www/html/admin/libraries/utility.functions.php on line 632

does anyone have experience with that issue? i’ve try to fwconsole restart/stop/start but did not work.


Here is the code that the error mentioning:

//write out crontab_
$exec = '/bin/echo "' . implode("\n", $cron_out) . '" | /usr/bin/crontab ' . $cron_user . '-';_
//dbug('writing crontab', $exec);_
exec($exec, $out_arr, $ret); // The 632 line_

return ($ret > 0 ? false : true);_