session_name() and session_start() is not working correctly

Question

i got this error on my pages

#1

PHP Warning:  session_name(): Cannot change session name when session is active in /dir/login.php on line xx
PHP Notice:  session_start(): A session had already been started - ignoring in /dir/login.php on line xx

#2

PHP Warning:  session_name(): Cannot change session name when session is active in /dir/other_pages.php on line xx

and the codes were like this on pages to check the SessionData

<?php
//set session name for each pages and start the session
session_name('AppName');
session_start();

...

// check if session is exist, if it exist then set the data, if its not then redirect to login pages
if(!isset($_SESSION['SessionData'])){
 //return to login page if session doesnt exist
 header("location:/login");
 exit();
}else{
 // get and set data from $_SESSION['SessionData'];
 $Data = $_SESSION['SessionData'];
}
?>

on login page (#1) it can set the session name and get the data, but when i go to other pages (#2) , there is no session data from $_SESSION['SessionData']. and when the session name supposed to be "AppName", it become "PHPSESSID". and it keeps redirecting to login pages even if the login is successfully

is there anything wrong with the codes or is it the php version? because iam using PHP 7.3 or is it the problem from the web server?

**#EDIT:** i tried to create a new file on ``/filename.php`` with this code

session_name('SessionExample');
session_start();

$_SESSION['example'] = "hello";
echo $_SESSION['example'];

and it can echoing "hello"

then i create another file /subdir/filename2.php with

session_name('SessionExample');
session_start();

print_r($_SESSION);
echo $_SESSION['example'];

but unfortunately it echoing nothing, and it only print null/empty array

while the session name was also PHPSESSID not SessionExample

is that really the whole script? Do you have any `include` or `require` statements before it? It might be starting a session there. — Barmar, Sep 02 '20 at 21:51
Another possibilty is you have `auto_prepend_file` configured in your `php.ini`, and that file is starting a session. — Barmar, Sep 02 '20 at 21:51
@Barmar theres no include/require except for composer library — Tunku Salim, Sep 02 '20 at 21:53
Sessions don't start by themselves. There must be some script calling `session_start()`. — Barmar, Sep 02 '20 at 21:54
See https://stackoverflow.com/questions/10648984/php-sessions-that-have-already-been-started for how to check if there's already a session. If there is, exit the session and start a new one with the name you want. — Barmar, Sep 02 '20 at 21:56
@Barmar yes, ive checked the other files and there is no session_start(), except for each pages but its not supposed to be like that, because it was working fine before but i dont know why — Tunku Salim, Sep 02 '20 at 21:57
@LawrenceCherone it was on line 2, which is the part where session_start() — Tunku Salim, Sep 02 '20 at 22:00
@Barmar i also checked the php.ini file and its only **allow_url_fopen=1** — Tunku Salim, Sep 02 '20 at 22:02

Barmar · Answer 1 · 2020-09-02T22:06:26.913

1

Check if the wrong session is already started. If it is, destroy the session and start the one you want.

if (session_status() == PHP_SESSION_ACTIVE && session_name() != 'AppName') {
    session_destroy();
}
session_name('AppName');
session_start();

edited Sep 02 '20 at 22:06

answered Sep 02 '20 at 22:01

Barmar

741,623
53
500
612

PHP Warning: Use of undefined constant SESSION_STATUS_ACTIVE - assumed 'SESSION_STATUS_ACTIVE' (this will throw an Error in a future version of PHP) in /dir/other_pages.php on line 2 PHP Warning: session_name(): Cannot change session name when session is active in /dir/other_pages.php on line 5 – Tunku Salim Sep 02 '20 at 22:04

score 1 · Answer 2 · answered Sep 02 '20 at 22:07

1

I think you cant open two session, so the error "A session had already been started" is because you try to open another session, you only have one session for the entire pages, but, you can have diferents session variable.

    if(session_status() == PHP_SESSION_NONE)
    {
        session_name('AppName');
        session_start();
    }

try to do this. PHP_SESSION_NONE check if the session has been started yet

the other thing i see in this code you dont set the session

if(!isset($_SESSION['SessionData']))
{
 //return to login page if session doesnt exist
 header("location:/login");
 exit();
}

so you need to set someting to the variable, or the program will continue go to login all the time beacause the session variable doesnt exists

if(!isset($_SESSION['SessionData'])){
//return to login page if session doesnt exist
 $_SESSION['SessionData'] = 'Data';
 header("location:/login");
 exit();
}

answered Sep 02 '20 at 22:07

Luis Monsalve

153
9

i dont really know whats the problem, at login page it can set the session and show it, but when it move to other pages the session is gone, i tried to print the session ``print_r($_SESSION)`` and it only show null array, but it can print the session on the login page – Tunku Salim Sep 02 '20 at 22:15
try to do `print_r($_SESSION['SessionData'])`, but put `$_SESSION['SessionData'] = 'Data';` in the if and then tell me if dont work – Luis Monsalve Sep 02 '20 at 22:28
you can try to erase the cache of your browser that make some problem sometimes or you can try this. before you do a header location. if(headers_sent()) { echo ''; echo ''; die(); } – Luis Monsalve Sep 02 '20 at 22:32
ive cleared my browser cache and do some test, but i still have the same problem – Tunku Salim Sep 02 '20 at 22:35

session_name() and session_start() is not working correctly

2 Answers2