I am currently developing an application with the PayPal online payment system. I already implemented the “PayPal Checkout” with the “Smart Payment Buttons” (https://developer.paypal.com/docs/checkout/#). I created a PayPal sandbox business account with which I test when I log in through my application. When testing with this account I get the data I need from PayPal (order id, amount, username of account, etc.) and I insert it in the database. Up to that point everything works fine, but I need a confirmation just to make sure (in case the web page freezes or goes down for some reason) the data was updated correctly in the database when the user pays the transaction through PayPal.
I decided to implement the PayPal IPN (Instant Payment Notification), a message system that notifies you of the events related to the PayPal transactions (https://developer.paypal.com/docs/classic/ipn/integration-guide/IPNIntro/). I used the sample code provided and modified it to fit my application (https://github.com/paypal/ipn-code-samples/blob/master/C%23/paypal_ipn_mvc_core.cs). I used the Postman application and sent a sample IPN message (https://developer.paypal.com/docs/classic/ipn/integration-guide/IPNIntro/#ipn-protocol-and-architect...) to my IPN listener and it worked. For the last step I published in the Development Environment with my local code and tested it with Postman and it worked. Now here is where the problem starts, I used the PayPal button to pay a transaction with the sandbox account previously created, but I dint receive an IPN from PayPal. I also used the IPN Simulator (https://developer.paypal.com/developer/ipnSimulator/) to send a message from PayPal and I received a “IPN was sent and the handshake was verified” displayed in the PayPal website but the data was not updated in the database. When I check the IPN history in the PayPal website to check if an IPN was sent at some point, it was empty (no IPN messages where sent). This Development Environment where my application now resides is in Azure Portal.
