PHP echo json_encode error

Severity: Warning
Message: Cannot modify header information - headers already sent by (output started at )


origin :

...
echo json_encode($myarray);

fix :

...
header("Content-type: application/json; charset=utf-8");
echo json_encode($myarray);
die;

References :
Output.php with compress_output = true, always calls ob_start(‘ob_gzhandler’) causing warning with ajax / Forums / Community / EllisLab