Cannot modify header information setcookie

Question

I recently upgraded from php 5.3 to php 5.6

But I received an error in my code:

Warning:  Cannot modify header information - headers already sent by (index.php:1) in core.php on line 2927

LINE 2927

setcookie(COOKIE_TOKEN, NULL, -1);

COOKIE_TOKEN is:

define('COOKIE_TOKEN', 'name');

Answer 1

Warning: Cannot modify header information - headers already sent

The issue is caused by $HTTP_RAW_POST_DATA : http://php.net/manual/en/migration56.deprecated.php

There's an example at the bottom that should help to confirm it:

<?php
    ini_set('always_populate_raw_post_data',-1);
    $HTTP_RAW_POST_DATA = file_get_contents('php://input');
    echo $HTTP_RAW_POST_DATA;
?>

http://php.net/manual/en/reserved.variables.httprawpostdata.php

PHP 5.6 deprecated automatically populating the HTTP_RAW_POST_DATA variable and introduced a deprecation notice. If the setting is left at the default value of 0 requests in the core can trigger this notice although HTTP_RAW_POST_DATA isn't being used or accessed.

See also: Warning about `$HTTP_RAW_POST_DATA` being deprecated

Answer 2

The warning is clear.

Warning: Cannot modify header information - headers already sent by (index.php:1) in core.php on line 2927

From http://php.net/setcookie :

setcookie() defines a cookie to be sent along with the rest of the HTTP headers. Like other headers, cookies must be sent before any output from your script (this is a protocol restriction). This requires that you place calls to this function prior to any output, including and tags as well as any whitespace.

Move that setcookie statement before any HTML appears: