NEED URGENT HELP :: Cart will sometimes not add items

i have tried the code several ways but i get the same issue no matter what.
sometimes the cart will now show items that have been added - ie its not accepting them and displayig them in the cart view.

I do not get any error.
when clicking "Add to cart" it goes to teh view cart page, but doesnt show the item just added.

THis only happens sometimes.
other times it accepts the items.
i cannot detect any pattern - its just random.

here is a few links to show you the issue for testing:
collection.php?S=SS210
collection.php?S=SS310
collection.php?S=SS410
collection.php?S=SS510

just randomly add any combinations to the cart
some will work - some wont.
i have even tried the same combinations - (ie same item with same color and same size) and gotten different results at different times.

ANY IDEAS ON WHERE TO TROUBLESHOOT THIS?

This post has been deleted.

I don't see anything adding to the cart.

to start with, download the sessionTest.php file from the following thread and upload it to your server to if there host has session management configured properly:
showpost.php?p=23826&postcount=2

if the sessionTest.php test successfully, then find the following line in your add to cart pages:

<?php

// WA eCart Redirect

if ($<your cart name>->redirStr != "")     {

  header("Location: ".$<your cart name>->redirStr);

}

?>

where <your cart name> is the name of your cart object.

and change it to:

<?php

// WA eCart Redirect

if ($<your cart name>->redirStr != "")     {

  session_commit();

  header("Location: ".$<your cart name>->redirStr);

}

?>

well i tested about 10 items and so far that code swap seems to have done the trick. out of curiousity what does the session_commit(); do? is this any indication of a server setting on my host that i should be aware of?

session_commit() forces the session to be written to the server.


There is a php bug that occurs on some servers where sessions created just before the using the header() function to redirect to another page will not be saved. session_commit() forces the session to be saved to work around the bug.

should i be concerned that the servers havent been updated?
is this bug only on older versions?

I haven't quite tracked down what causes this to happen on some hosts. It shouldn't be necessary, but we have run into it enough to know how to fix it.

I can't say for sure if you should be concerned or what precise versions have this issue... we just don't know. I think it has something to do with the CGI version of php 4 on a windows machine. Is that what it says you are running when you view phpinfo()?