Headers already sent in php

Question

Recently I worked in a project there I wrote the following code in top of the page:

<?php 
session_start();
include_once('../module/connection.php');
$_SESSION['lang']=$_GET['ses'];
if(($_SESSION['lang']=='') || ($_SESSION['lang']=='english'))
{
  $l='japanese';
}
else if($_SESSION['lang']=='japanese')
{
  $l='english';
}

When I run that page it shows the following warning:

Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at /var/www/sites/subdomains/www/html/ussl/juu/area/index.php:1) in /var/www/sites/subdomains/www/html/ussl/juu/area/index.php on line 1

How can I solve this?

Answer 1

Is there any whitespace or other characters before your first "<?php" ? That would count as output. Also see this question. As is said in the error message, there's something in /var/www/sites/subdomains/www/html/ussl/juu/area/index.php on line 1. If your code snippet above is not from that file, go check it.

Answer 2

I would guess you've got some text before your <?php tag, which is essentially sending HTML to the client and thus headers are already sent. Anything there?

Answer 3

You are outputting something before the use of session_start().

Make sure that there is nothing (by nothing I mean not even white-space) before <?php.

---

EDIT: As an alternative, you can add the following before session_start().

ob_start(); ob_clean();

I do not recommend using this workaround. Always find the cause of the problem and correct it instead of applying a workaround. Use the workaround only in last resort.

Answer 4

It sounds like maybe your webhost is sending the headers for something like adverts/banners?

Answer 5

check your logs for errors with session read/write permissions

Answer 6

i had the same problem,
make a new php file, copy all lines from index.php but the first line it worked for me