PayPal Website Payment Standard Error

In the last 10 days I had received 3 orders through PayPal standard payment that were never synced to Zen Cart. In the same period I have received more than 100 orders via PayPal that were synced normally to Zen Cart. I have activated the debug mode for that module a few days ago.

The following is one of the errors I found in log

Apr 11 2011 18:35 -- PDT PROCESSING INITIATED.
Preparing to verify transaction via PDT.

The TX token for verification is: Array
(
[main_page] => checkout_process
[referer] => paypal
[tx] => 89S97409E1872313G
[st] => Completed
[amt] => 320.48
[cc] => USD
[cm] => zenid=0bd86a62238a3e1ee3bbb35f3bb654a3
[request] => nonajax
)

Apr 11 2011 18:35 -- IPN INFO - POST VARS to be sent back (unsorted) for validation (using CURL):
To: www.paypal.com:80
Array
(
[cmd] => _notify-sync
[tx] => 89S97409E1872313G
[at] => D_HUw**********MziB0
[request] => nonajax
)

Apr 11 2011 18:35 -- CURL OPTS: Array
(
[10002] => https://www.paypal.com/cgi-bin/webscr
[47] => 1
[10015] => cmd=_notify-synch&tx=89S97409E1872313G&at=D_HUwdslGdQA4D-M9fJjI1fsCUtHyeRlGySB1O2bzqvFAz0RUkxqdfMziB0D_HUwdslGdQA4D-M9fJjI1fsCUtHyeRlGySB1O2bzqvFAz0RUkxqdfMziB0&request=nonajax
[13] => 45
[78] => 30
[41] => 0
[42] => 0
[52] => 0
[19913] => 1
[64] => 0
[81] => 2
[75] => 1
[74] => 1
[84] => 2
[10018] => Zen Cart(tm) - IPN Postback
)

Apr 11 2011 18:35 -- CURL response: FAIL
Error: 4020

Apr 11 2011 18:35 -- IPN INFO (cl) - Confirmation/Validation response FAIL

Apr 11 2011 18:35 -- PDT Returned INVALID Data. Must wait for IPN to process instead.
Array
(
)

Switch to PayPal Express

Where's the "request=nonajax" coming from?

And, kobra's right: dropping the WPS module in favor of the EC module will eliminate your dependency on PDT and IPN postbacks for verification.

Where's the "request=nonajax" coming from?
I am using Ajax checkout for the store...

I like using the standard payment module... I shop a lot online and a lot of large companies still use the standard payment.

If that ajax-related parameter gets sent back to PayPal as part of the page's parameters (part of the PDT verification process), it's going to reject it.

Have you tested turning OFF your ajax-checkout addon and see whether things suddenly work better?

That module been there for years, nothing changed on the site in the months... It only happened 3 times in the last month. I had more than 200 good orders through PayPal in the same process... My only guess is 2 people ordering at the same time using PayPal.

Update!
This issue happens only when there are 2 or more items in the order.

Another update.

Express Checkout doesn't work for me so I switched back to IPN.

I am guessing the issue has to do with Free Shipper Module. Ever since I start using this module things started going down hell.

I read on the forum that the Free Shipper will not function well with multi-zones stores. I do have like 5 different zones.

I just got an order from PayPal IPN, It is not registered in my store database. The customer bought 2 items, which are the only 2 items that are using the Free Shipper rule. But even though they are suppose to be Free Shipping he was charged shipping.

Hope this clarify it a little bit more for Dr Byte.

Without seeing the IPN logs I can't do much else than simply sigh.

The log was off, I will have to wait for another order with 2 items.