paypal sandbox responds bad request

Question

I have following HTML form

<form action="https://sandbox.paypal.com/cgi-bin/webscr" method="post" id="paypalpost" name="paypalpost">
                <input type="hidden" name="rm" value="2"/>
                <input type="hidden" name="cmd" value="_xclick">
                <input type="hidden" name="business" value="[email protected]">
                <input type="hidden" name="item_name" value="Wedding Gift">
                <input type="hidden" name="currency_code" value="EUR">
                <input type="hidden" name="amount" value="<?php echo $value['total'];?>">
                <input type="hidden" name="return" value="http://developwithus.com/wedding/return.php">
                <input type="hidden" name="cancel_return" value="http://developwithus.com/wedding/return.php?status=0">


            <input onclick="return submitatoc();" disabled type="submit" name="submit" id="pay" class="buttonBlueBg" value="Checkout" style="cursor:pointer;">

            </form>

---

I had mentioned return URL as http://developwithus.com/wedding/return.php on which, (I had download this from : https://cms.paypal.com/cms_content/US/en_US/files/developer/IPN_PHP_41.txt and add

<?php 
print_r('<pre>');
print_r($_POST);
// read the post from PayPal system and add 'cmd'
$req = 'cmd=_notify-validate';

foreach ($_POST as $key => $value) {
    $value = urlencode(stripslashes($value));
    $req .= "&$key=$value";
}

// post back to PayPal system to validate
$header .= "POST /cgi-bin/webscr HTTP/1.0\r\n";
$header .= "Content-Type: application/x-www-form-urlencoded\r\n";
$header .= "Content-Length: " . strlen($req) . "\r\n\r\n";
$fp = fsockopen ('ssl://www.sandbox.paypal.com', 443, $errno, $errstr, 30);

// assign posted variables to local variables
$item_name = $_POST['item_name'];
$item_number = $_POST['item_number'];
$payment_status = $_POST['payment_status'];
$payment_amount = $_POST['mc_gross'];
$payment_currency = $_POST['mc_currency'];
$txn_id = $_POST['txn_id'];
$receiver_email = $_POST['receiver_email'];
$payer_email = $_POST['payer_email'];

if (!$fp) {
// HTTP ERROR
    echo "HTTP Error";
} else {
    fputs ($fp, $header . $req);
    while (!feof($fp)) {
        $res = fgets ($fp, 1024);
        echo $res;
        if (strcmp ($res, "VERIFIED") == 0) {
            // check the payment_status is Completed
            // check that txn_id has not been previously processed
            // check that receiver_email is your Primary PayPal email
            // check that payment_amount/payment_currency are correct
            // process payment
            echo("verified");
        }
        else if (strcmp ($res, "INVALID") == 0) {
            // log for manual investigation
            echo ("invalid");
        }
    }
    fclose ($fp);
}
echo "end";
?>

but I got Bad Request as response, If I go to paypal sand box account and made payment and return back.

Array
(
   [CONTEXT] => wtgSziM4C5x0SI-9CmKcv2vkSeTLK5P_g6HqzC__YTYkcqziFNcB84p79Ja
   [myAllTextSubmitID] => 
   [cmd] => _flow
   [mc_gross] => 100.00
   [protection_eligibility] => Ineligible
   [address_status] => confirmed
   [payer_id] => Z5NWSYYVZW268
   [tax] => 0.00
   [address_street] => 1 Main St
   [payment_date] => 09:04:08 May 14, 2011 PDT
   [payment_status] => Pending
   [charset] => windows-1252
   [address_zip] => 95131
   [first_name] => Test
   [address_country_code] => US
   [address_name] => Test User
   [notify_version] => 3.1
   [custom] => 
   [payer_status] => verified
   [address_country] => United States
   [address_city] => San Jose
   [quantity] => 1
   [payer_email] => [email protected]
   [verify_sign] => AozIjtjfCe0jUnbJpR4qPrW54olKAq.SrnEktGSocrk8yYv4bpR4lJX7
   [txn_id] => 3HG58230W32603443
   [payment_type] => instant
   [last_name] => User
   [address_state] => CA
   [receiver_email] => [email protected]
   [pending_reason] => unilateral
   [txn_type] => web_accept
   [item_name] => Wedding Gift
   [mc_currency] => EUR
   [item_number] => 
   [residence_country] => US
   [test_ipn] => 1
   [transaction_subject] => Wedding Gift
   [handling_amount] => 0.00
   [payment_gross] => 
   [shipping] => 0.00
   [merchant_return_link] => click here
   [form_charset] => UTF-8
)
HTTP/1.1 400 Bad Request
Date: Sat, 14 May 2011 16:05:20 GMT
Server: Apache
Set-Cookie: c9MWDuvPtT9GIMyPc3jwol1VSlO=%7cgA9mW0Yh7-iBp435VBDwyCqtOtnlE8KAk8fT_sjGXHGx2mDzXgFit5ZdHd3BOOEUt_UDRW%7cRD1g8aAyLevIAP-u4WfCokEQkimrkpQk6v6rLZ_xD-pT1ATWuv5RtcK3NIbPPwfF1cXq3G%7c; domain=.paypal.com; path=/; Secure; HttpOnly
Set-Cookie: cookie_check=yes; expires=Tue, 11-May-2021 16:05:20 GMT; domain=.paypal.com; path=/; Secure; HttpOnly
Set-Cookie: Apache=10.191.196.11.9095130538912094; path=/; expires=Fri, 31-Mar-05 09:37:04 GMT
Connection: close
Content-Type: text/plain; charset=ISO-8859-1

can you guys tell me what I'm doing wrong? INVALID response is working

Answer 1

Remove your *.paypal.com cookies.
This an unfortunate bug in the PayPal system, where the cookie gets too large and the server errors out on it.
You can avoid the problem by using two different browsers, e.g. IE for PayPal Live and FF for the PayPal Sandbox.