Why did I get HTTP error code 429?
PayPal returned HTTP error code 429 - Too many requests.
Cause
If more than 50 requests are received from an IP address (cumulative hits of all endpoints) within 1 minute, PayPal Sandbox will block the IP for the next 5 minutes.
Solution
To prevent your IP address from becoming temporarily blocked, limit the number of requests to be fewer than 50 per minute.
See also:
Rate limiting guidelines