Undefined variable: _SESSION when sending variables via post through JavaScript trigger

Question

In my index.php file I call session_start() and set a couple of session variables. In a second PHP file I would like to access these session variables.

Answer 1

session_start();  

is the answer of most of topic like this. i have been struggling with this issue and i solve my problem with this code

    if (version_compare(PHP_VERSION, '5.4.0', '<')) {
        if(session_id() == '') {session_start();}
    } else  {
       if (session_status() == PHP_SESSION_NONE) {session_start();}
    }

Answer 2

I had this problem and tried different ways and finally found a solution :

PHP is case sensitive, Use $_SESSION instead of $_session in all php files.certainly It works . Example :

<?php
session_save_path('tmp/'); (is not optional - it is mandatory)
session_start();
echo $_SESSION["s1"]."<br/>";
echo $_SESSION["s2"]."<br/>";
?>