Common HTTP error codes

Code	Error Description
400	Missing or bad request parameters or values
403	Session expired or invalidate. Must relogin
404	Request resource was not found
405	Request method (GET, POST etc.) is not allowed on the requested endpoint
410	The requested resource is gone permanently
429	Too many requests to the API (rate limiting)
500	Something unexpected went wrong
502	The backend OMS is down and the API is unable to communicate with it
503	Service unavailable; the API is down
504	Gateway timeout; the API is unreachable