PHP sessions that have already been started [duplicate]

In my PHP code, if a session has already started, and I try to start a new one, I get the following Notice:

Notice: A session had already been started - ignoring session_start()

How can I avoid this?

Try

<?php
    if(!isset($_SESSION)) 
    { 
        session_start(); 
    } 
?>

If you want a new one, then do session_destroy() before starting it. To check if its set before starting it, call session_status() :

$status = session_status();
if($status == PHP_SESSION_NONE){
    //There is no active session
    session_start();
}else
if($status == PHP_SESSION_DISABLED){
    //Sessions are not available
}else
if($status == PHP_SESSION_ACTIVE){
    //Destroy current and start new one
    session_destroy();
    session_start();
}

I would avoid checking the global $_SESSION instead of I am calling the session_status() method since PHP implemented this function explicitly to:

Expose session status via new function, session_status This is for (PHP >=5.4.0)