Sandbox IPN URL throwing 404 Error

[davegolfer_22]

Hi,

I am not able to validate the IPN I am getting after completing a sale in the sandbox environment.

The URL I'm using is: https://ipnpb.sandbox.paypal.com/cgi-bin/webscr 

I have also tried what I think is the old one: https://www.sandbox.paypal.com/cgi-bin/webscr

It throws a 404 error code. Is there something wrong with the url?

Thank you

[davegolfer_22]

I'm still having this problem and haven't heard anything yet. It was working on March 14, 2023 but was not on the morning of the 15th. Is there a problem with the sandbox IPN verification?

[davegolfer_22 · Accepted solution]

The problem ended up being a result of adding the cmd=_notify-validate parameter at the end of the list of parameters for the validate request posted back to PayPal instead of at the beginning. I put it at the beginning to fix the problem.

Note that I had been using this code since 2016 without a problem until now.