Wordpress header error?

Question

PHP

The site encountered an error
Warning: Cannot modify header information - headers already sent by (output started at /var/www/vhosts/u0036288.plsk.regruhosting.ru/httpdocs/rcentr-ug.com/wp-content/themes/rcentr -ug/header.php:6) in /var/www/vhosts/u0036288.plsk.regruhosting.ru/httpdocs/rcentr-ug.com/wp-content/plugins/aws-cabinet/includes/shortcodes.php on line 109
line from header.php:6

<title><?php bloginfo('name'); ?><?php wp_title(); ?></title>

line from shortcodes.php on line 109:

setcookie("id", $data->base_id, time()+60*60*24*30, "/");

The site was working fine, and all of a sudden this error appeared...didn't do anything to the site before! Encoding of both UTF files without BOM.
What could be the problem, please help!

Answer 1

There was also a similar problem. I had to refuse to set cookies through a shortcode.
Attached an event handler

add_action( 'init', 'set_cookie'); 
function set_cookie(){
if(isset($_POST['base_id']))
   setcookie("id", $_POST['base_id'], time()+60*60*24*30, "/");
exit;
}

Answer 2

Cookies are set after string output has already been done.

Answer 3

Registered at the beginning
<? ob_start();?>
and at the end of the page
<?ob_end_flush();?>
Everything worked....