A developer is trying to retrieve data over a REST API.

The HTTP client error response code accompanied by a Retry-After header typically indicates that the client has sent too many requests in a given amount of time, leading to rate limiting by the server. This is often indicated by a 429 Too Many Requests status code. The Retry-After header informs the client how long it should wait before making another request.

References:

Cisco DevNet Associate Study Guide: REST API Error Handling (Chapter 7, Section: Understanding HTTP Status Codes).