Some IPNs are being rejected by host server

**whitknits** · 14 Mar 2010, 12:13 AM

My site has been operating for a couple of years without any Paypal issue, but as of March 1, I started getting emails from Paypal that say IPNs sent to the following url are failing. No order is generated in ZC as a result. IPNs do not fail if someone is a returning customer or if they create the account and come back later and make a purchase. It just seems to happen when a customer registers and orders in the same session. Today I checked IPN history on my Paypal account and learned that IPNs have also failed when I make a partial refund in that nothing changes in ZC. Curiously, today I received an order and it did generate in ZC, but Paypal lists it as one where the IPN failed. I have been to both my developer, who hosts my site along with a small number of other sites, and Paypal. Paypal claims it is a problem with my host, but she has not changed anything and has never heard of this as an issue. Everything appears to be set correctly and so I am at a loss. Has anyone ever dealt with this before?

**whitknits** · 14 Mar 2010, 05:39 PM

Just want to add that I am using 1.3.8 and I believe all the recommended patches have been installed.

**DrByte** · 14 Mar 2010, 06:01 PM

If the problem is constantly persistent, and happens with *all* IPNs sent from PayPal, then you'll need to either fix the firewall problem in your server that's preventing the IPNs getting through, or fix the PHP problem that's causing the ipn_main_handler.php script to fail without acknowledging the IPN receipt from PayPal.

If the problem is intermittent, then we know it's actually functional and therefore that the PHP is fine and the firewall is fine. Thus the problem must be with something between PayPal's server and your server. That would be the internet in general as well as your hosting company's network infrastructure.

Also, you mentioned "as of March 1 ...". You should take note that PayPal just recently re-enabled their IPN alerting system, and I'm convinced that they have some bugs in it which are raising false positives in their tests.

It would be interesting to discover whether the particular IPNs you're saying are failing are unique to a certain type of transaction. If they're all sales and are all essentially identical to actual good and completed IPNs, then there's not much we can do to blame the code. But if it's something like just refunds getting rejected but all the sales are fine, then one could attempt to dig into seeing what may be damaged in the code on your site. If there *is* a pattern, I suggest you point it out to PayPal specifically. And it's probably worth explaining the details here. But based on what you've posted here so far, I can't see any reason for intermittent failures to occur.

**whitknits** · 15 Mar 2010, 12:20 AM

As far as I can tell, the pattern of failed IPNs is what I put in the first post - for new customers who sign up and order in the same visit and for refunds. Paypal shows IPNs as retrying even on ones where an order was created in ZC. According to Paypal, my host server is not sending back the 200 ok message and that is why Paypal keeps retrying.

Could any of this be helped by switching to express checkout?

**DrByte** · 15 Mar 2010, 12:57 AM

Originally Posted by whitknits

Could any of this be helped by switching to express checkout?

Lots of things can be fixed by making that change. However I can't guarantee that the issue you're discussing will be resolved by it.

**DrByte** · 15 Mar 2010, 01:00 AM

Originally Posted by whitknits

As far as I can tell, the pattern of failed IPNs is what I put in the first post - for new customers who sign up and order in the same visit and for refunds.

Turn on debug logging (to file) and do some transactions (you or your customers), and trigger the alleged IPN failure. Then collect all the debug logs, zip them up, and upload the zip to your server someplace, and PM me with the URL link to that file. I'll review the logs to see what patterns emerge. Knowing the transaction IDs of the failed IPNs listed in your paypal profile will help me audit and match potential issues in the logs, too, so please include some of those details in the PM.

ref: http://www.zen-cart.com/forum/showthread.php?t=61199

**whitknits** · 16 Mar 2010, 03:34 PM

Hi Dr. Byte,

My developer just explained that now that I am using Paypal Express and IPN is turned off, the emails that I still receive from Paypal are from when IPN was turned on. This makes sense since I believe Paypal will keep trying to get through up to 16 times. So far the cart seems to be working correctly and orders are being created. I am going to wait and see if this continues, but wanted to thank you for your offer to help. I really appreciate it and may have to take you up on it at a later date.

Thanks,

Nancy