PayPal Express checkout IPN notification bug
IPN (instant payment notification) is a background call to user script from PayPal which is suppose to notify website owner about payment events. This is complementary non required service website owners can use to detect payment result instantly. To be honest from experience this is must have since too many users get lost in payment process on paypal side and they never come back to origin website. This causes incomplete orders on web shops.
IPN works this way:
1. You enable service in paypal merchant account settings and give URL where you want paypal to send postback to.
2. You catch postback data in your script and precede it with one more field called “cmd” with value “_notify-validate”
3. Post all received data with preceded command back to paypal
4. Paypal should answer VERIFIED or INVALID. This should tell you whether post-back is genuine or not and whether you can proceed with order accordingly.
However lately PayPal response to verification command with 500 internal server error message. Therefore you can’t find out result of verification and because you cannot trust the post-back you should drop it. Another problem is that PayPal marks this post-back as completed successfully and postback repeat cycle stops, you can see this in history of IPN calls in merchant account on PayPal.
This issue effectively breaks all your payment notifications. For now only option is to drop verification and trust the post back implicitly unless you want to check payment status yourself in PayPal merchant account all the time.
Some people say they are able to find workarounds by removing empty fields from verification or so, however this is making entire system not compliant with PayPal implementation manual and it is likely to stop working again. Also doing this can make PayPal post-back not reliable.
We’ve posted this bug to PayPal support and they confirmed problem at their side, check out PayPal answer below and stay tunned for resolution of the problem.
Dear Stan,
Thank you for contacting PayPal Merchant Technical Services.
With regard to your query on the 500 – internal server error upon IPN verification/validation I can inform you of the following.There is currently a known issue in our system that caused this.
Our engineers are working on a fix.For the moment therefore we would recommend to temporarily disable the default IPN verification and use the GetTransactionDetails API call for the verification if you wish.
More on this API here: https://www.paypal.com/en_US/ebook/PP_APIReference/gettransactiondetails.htmlAs you’ll know the IPN messages are still arriving at your server/IPN listener.
Should you require any additional information, please feel free to contact us.
Thank you for your understanding while we work to resolve the issue.
You will be updated through this ticket once there is an update on the issue.Kind regards,
Gino
Merchant Technical Services
PayPal, an eBay company
Published by Stan Kuhn in: Bugs & issues
4 Comments to “PayPal Express checkout IPN notification bug”
There are a lot of angry people out there because of this. It seems to be taking a long time to fix. I first saw it reported at the end of March.
500 internal error seems to be fixed, I noticed it started to show in our logs results Verified on 10 of May but got confirmation from paypal just now.
Response (Administrator) 05/19/2010 09:53 PM
We appreciate your patience. This message is to inform you that the issue was resolved through a recent live site update.
Please contact us again if you feel the issue is not resolved and provide additional supporting details to help us identify or reproduce the issue.
PayPal Merchant Technical Services
I am using a script to sell downloads. And many times a customer will not receive a password or username or a welcome email from my site on multiple purchases (usually when they have more than 8 or so products in their shopping cart). I thought something was wrong with my site. I looked into the IPN settings and the field for the URL on PayPal’s IPN page is empty. I don’t know what to put in that field. I get “zero” help from my sites developer so any help would be appreciated. Thanks, Dave
Hi Dave. IPN paypal service is not must have. You may be using paypal checkout without IPN. If your IPN url in paypal account is empty it doesn’t necessarily mean something is badly configured. On the other hand if you are using pay button or simple cart solution from our experience integration without IPN leads to quite a lot “unprocessed orders”. This is due the fact that without IPN your website gets notified about result of payment only when customer goes back to your website straight after payment. Which many times doesn’t happen for various reasons. So if there is some functionality on your website happening on successful payment notification like update of stock or order status or send email to customer these may not happen always. If your IPN configuration does not contain URL you can be sure you haven’t got it activated. You need to have script on your website which is able to receive and process IPN notification from paypal, you must know about it to know what to put in IPN configuration.
If you need commercial help with your website drop me an email stan@lampwebde…..