问题
What is wrong with my Paypal sandbox account process to receive webhook notifications? We are unable to receive webhook event on my URL.
URL working with "Webhooks simulator". Please let me know what should I do for receive webhook event on above URL.
回答1:
Webhooks simulator sends sample payloads for the events you configured. It does not send a notification on triggering of an actual event.
If you are getting notification via Webhooks Simulator, it means the URL configured by you is able to intercept POST requests.
Now for the "Paypal sandbox account unable to process to receive Webhook notifications" part, please check if the transaction is actually created at https://developer.paypal.com/developer/dashboard/sandbox/ . If the transaction you are looking for is not present there, there won't be any notification generated. In case transaction is present there and still you are not getting any notifications, please share debug id.
回答2:
Here is a silly thing that I overlooked in the documentation and only found out after contacting support.
After you've followed the approval url and gave your approval, dit you execute the payment with the REST API?
https://developer.paypal.com/docs/api/payments/#payment_execute
Webhooks are only called after you've executed the payment.
The confusing part is; there is no webhook being called, when a user approves or cancels a payment. There is only a redirect back to a return url or cancel url. So you either need to monitor the redirect back to your site and trigger the execute call then, or find another way (like polling the payment) to see the status change before calling the execute call.
来源：https://stackoverflow.com/questions/34737579/regarding-uable-to-trigger-paypal-rest-api-webhook-events-from-developer-sandbox