session_start(): Cannot send session cache limiter - headers already sent

Question

I am not sure why, it gave me this error, and my session_start(); is already at the first line. The codes work before, but i altered the sql query, then it gave me that error.

Here is my code.

<?php

ini_set('display_errors', 1); error_reporting(E_ALL);

session_start();
include 'connect.php';







$_SESSION['username'];
$_SESSION['id'];
$userid = $_SESSION['id'];


//Using session username to pull out variables from Table

$result=mysqli_query($con,"SELECT ......);





while ($row1 = mysqli_fetch_assoc($result))

        {

   $output[] = $row1;
        }
        if (!empty($output)){
        echo json_encode( $output );}
        else{
            echo json_encode( [] );
        }
?>

do you include other file that contain session_start()? what i mean is at same page. — user3517652, Apr 17 '14 at 05:58
what is content of `connect.php`, is it too having `session_start()` ? — Ravi Dhoriya ツ, Apr 17 '14 at 05:59
You can change `echo json_encode( [] );` to `echo '[]';`... it isn't an error but json_encode is doing nothing anyway because it's an empty data set. — Justin Mitchell, Apr 17 '14 at 06:03
Hi, no session_start() in connect.php, and the other files, none of them have this error. Really not sure why. And thanks Justin will change that in a little. — Benyaman, Apr 17 '14 at 06:05

score 2 · Accepted Answer · answered Apr 17 '14 at 06:00

2

According to the PHP manual, the error happens when some sort of output has happened before session_start is called. This is especially so if you're displaying errors. This could be a space before the <?php tags at the top of the document, or it could be because of a warning from deprecated code, or from missing variables or an error from a missing ; or other type of character. The best thing to do is to log any errors to a file and then review the file after you execute.

Try moving the session_start() to the top of the document and also check that session_start() isn't called by any other file or class or function anywhere else in your code.

answered Apr 17 '14 at 06:00

Justin Mitchell

339
1
5

Hi, Thanks i resolved it, i moved session_start(); to the top and just realised there was a single empty space before – Benyaman Apr 17 '14 at 06:08
It's probably **the** most common cause of this issue – Justin Mitchell Apr 17 '14 at 06:16
In my code, its literally the first char. I even checked by using notepad++ and I cant seem to find any extra chars... I still get the warning... waht am I doing wrong? – ullfindsmit Aug 24 '19 at 04:57

score 1 · Answer 2 · edited May 23 '17 at 12:20

"Cannot send session cache limiter - headers already sent"

"Headers already sent" means that your PHP script already sent the HTTP headers, and as such > it can't make modifications to them now.

Check that you don't send ANY content before calling session_start. Better yet, just make > "session_start" the first thing you do in your PHP file (so put it at the absolute beginning, > before all HTML etc).

Hope it helps.

session_start(): Cannot send session cache limiter - headers already sent

2 Answers2