Edit: I fixed it, the problem was the spaces before <?php.
Thanks for the comments.
Sessions are working on all pages except index.php
The error: session_start(): Cannot start session when headers already sent in /home/site/public_html/connection.php on line 13
connection.php:
<?php
try {
$db=new PDO('mysql:host=localhost;dbname=testdb','testuser','123456');
$db->exec("SET CHARACTER SET utf8"); }
catch(PDOExpception $e) {
echo $e->getMessage(); }
ob_start(); session_start(); # (line 13)
?>
index.php:
<?php
include 'connection.php'; include 'seo.php';
$connect_site=$db->prepare("SELECT * FROM site WHERE id=?");
$connect_site->execute(array(1));
$site=$connect_site->fetch(PDO::FETCH_ASSOC);
?>
<!DOCTYPE HTML>
<html>
<head>
...
