Problem with "headers already sent" errors

I've been developing on a Mac (DW CS5, eCart 5) and testing on a Linux web server.
The site has been working fine on both platforms.

In the past few weeks I've made a few changes. The site is still working fine on my Mac development platform (I use Apple's apache) but when I uploaded the new chagnes to the Linux test server I have been getting errors on some pages about "headers already sent".

I looked up some info on the web and found a lot of talk about not having spaces or even line returns between PHP tags, or else making sure start_session() happens at the top of the page. I tried both things, and they seemed to help fix the problem (the error stopped showing up).

Than, later, for various reasons I ended up taking those changes back out (I put line breaks between php tags), and strangely enough the pages continued to work without showing errors.

Now, however, I have one last page that is showing the "headers already sent" error and I cannot fix it. I'm really not able to remove all the spaces and returns for the whole page all the way down to where the problem is (line 291).

The exact error I'm getting on this page (checkout_success.php) is:

Warning: session_regenerate_id() [function.session-regenerate-id]: Cannot regenerate session id - headers already sent in /var/www/clients/client5/web9/web/checkout_success.php on line 291

The file is attached.

Can you please let me know what I can do to fix this error?

I develop in almost exactly the same environment except I use MAMP Pro rather than the inbuilt Apache Server.

I also had trouble with this issue and what I ended up doing was adding an extra page to the checkout process that stored the order before transferring to the checkout success page and then putting this code at the top of my checkout_success.php file

<?php

// Initialize the session. 

session_start(); 



//store the sessions required for this page

$userSession = $_SESSION['clientID'];

$orderNumber = $_SESSION['orderID'];



session_destroy();  

unset($_SESSION); 

session_start(); 

session_regenerate_id();



//reset user session 

session_start();

$_SESSION['clientID'] = $userSession;

$_SESSION['orderID'] = $orderNumber;

?>

Then pull the order and customer information from the database to display on the page and at the bottom of the page destroy the remaining session variables.

Dave I really appreciate the reply.

I would like a Web Assist tech to repsond if possible and tell me what's wrong with the current page. I could add another page if it was absolutely the only solution, but the checkout process is already many pages long, I really don't want to add another one.

Does anyone know what it is that actually causes this problem?

To me, it is very strange that all the other pages work fine and just a couple of them display this error ... what causes it?

Thanks

change:
<?php session_regenerate_id(); ?>


to:
<?php @session_regenerate_id(); ?>

Amazing! Thank you Jason that fixed it. I've been pulling my hair out over this one for almost 24 hours now.

Could you please provide some technical instruction about what the @ does and why it fixes the problem - I would like to understand it better.

I saw your recommendation to use the @ in some similar posts on this forum (@setcookie ....) but I didn't know exactly where to put it in my case.

the @ suppresses errors.


it basically means do something, but if an error is encountered, don't display it an d keep moving.