User Guide

IPN Guide June, 2009 29
IPN Testing
IPN Troubleshooting Tips
4. Click Send IPN.
The IPN message is sent to the specified URL and the results of the operation are displayed
at the top of the page.
After Completing This Task:
If your IPN listener receives a message, you know that it is properly installed on your web
server. The default messages sent by the IPN simulator are valid, thus, if your listener responds
correctly to the message, it should receive a VERIFIED message. If you do not receive any
message or if you receive an INVALID message after responding to the original message from
PayPal, you will need to troubleshoot your listener.
IPN Troubleshooting Tips
IPN failures fall into three categories: not receiving any IPN messages from PayPal, receiving
some but not all IPN messages, and receiving INVALID messages from PayPal after
responding to a message.
If you do not receive any IPN messages from PayPal
z Check the IPN History page on PayPal. It tells you whether PayPal sent the IPN message
and whether your listener responded to it. It may also provide information about the status
of the server on which your listener is running. If necessary, from this page you can also
request that PayPal resend the IPN message.
z Check that the path to your IPN listener is correct and you are using that path correctly in
your IPN notification URL; for example, the file path is often similar to, but not the same
as, the URL.
z Verify that your firewall settings are not blocking HTTP POST messages from PayPal.
z If the logs for your web server are available, check the logs to confirm that messages are
being sent to your web server and check for any errors that may have occurred.
If you receive some messages but not others
z Verify that your IPN listener is responding to all messages, even those you do not intend to
process.
z Check that the account is valid and confirmed; for example, if you send money to an
unconfimred account, PayPal does not send an IPN message.
If you receive an INVALID message
z Check that your are posting your response to the correct URL, which is
https://www.sandbox.paypal.com/cgi-bin/webscr or
https://www.paypal.com/cgi-bin/webscr, depending on whether you are testing
in the Sandbox or you are live, respectively.
z Verify that your response contains exactly the same IPN variables and values in the same
order, preceded with cmd=_notify-validate.