499 Client Closed Request
HTTP response status code
499 is an unofficial HTTP status code that is specific to both ArcGIS with
499 Token Required and nginx with
499 Client Closed Request.
499 Token Required status code is received, the server is expecting a token in the HTTP request but it was not submitted.
499 Client Closed Request status code is received, it means that the client has closed the HTTP Connection in advance of the server completing the task. As such, the final response cannot be sent and this status code is only available in the nginx logs.