PayPal IPN Simulator: IPN was not sent, and the handshake was not verified. Please review your information

Question

"IPN was not sent, and the handshake was not verified. Please review your information." This is the error I get on the PayPal IPN Simulator page after I click the blue “Send IPN” button at the bottom.

The listener I'm using is copied from: https://github.com/paypal/ipn-code-samples/blob/master/paypal_ipn.php I saved this posted code to a PHP file, and named it listener.php; then I uploaded it to our website.

My PHP is version: 5.5.37

There's actually quite a bit about this very error on SO, but I'm not finding anything that seems to help. None of the answers I looked at were accepted, and or seemed to be the issue I'm having.

I read this: IPN was not sent, and the handshake was not verified. Please review your information. I didn't know where to run the connection script against PayPal. But I did put my website into shachecker.com I got a "Nice XXXX has a verifiable certificate chain signed with SHA-2."

On the PayPal IPN Simulator page, I've been putting in the full URL for my listener in the "IPN handler URL" field. Then I've been selecting "Cart Checkout" or "Web Accept" in the Transaction Type field.

Today my code won't produce any updates in the ipn.log, after I click the "Send IPN" button; unless I physically open my listener.php page in a web browser. Then it produces the file: ipn.log

Before today it was working better. I would get a reply of INVALID. So I looked at this URL and checked through the list posted there: https://developer.paypal.com/docs/classic/ipn/integration-guide/IPNTesting/#invalid

I wasn't able to verify the ordering of the variables, or see that they were the same because it quit working today. But I can verify the page is using the correct URL, the message is preceded by cmd=_notify-validate , and it is UTF-8 .

This whole adventure has been difficult to debug because there's just no output, or error logs that I can see. (If anyone's done this before and had success, please let me know.)

I'm attempting to use IPN because our current website depends upon a post-back from PayPal, to get notification that the order has completed. But we've found that PayPal doesn't always return back to the website. IPN was advertised as being much more reliable. But I'm open to any other suggestions as well. Thanks so much!

Answer 1

It's funny how this got resolved. I followed Asmir Zahirovic's advice and I emailed the company that's hosting our site. He assured me that they use PayPal's IPN for many of the sites they host, including for their own needs.

Then I remembered that someone wrote, somewhere, that PayPal's IPN Simulator just didn't work for them, but production did.

I followed the steps, PayPal outlined, to make sure the listener was enabled and turned on. (Still IPN Simulator did not work.)

Then I set my listener to production mode, and just waited. In a couple days, we had an order come through and my listener got, it from PayPal; and it came through as VALID.

So to anyone reading this, the PHP listener code from GitHub works just fine. Just go to production ; PayPal's IPN Listener may not work.