| 400 | Malformed request, invalid query or path parameters, or failed basic validation. |
| 401 | Request rejected for authentication (when a deployment uses this code). Invalid transaction signatures are typically returned as execution errors. |
| 403 | Sender is not allowed to perform the action (for example, not a delegate of the trader account). |
| 404 | Unknown path or resource id. |
| 409 | Conflict with current state (when the API uses this code). |
| 422 | Well-formed JSON but business-rule or semantic validation failed. |
| 429 | Rate limit exceeded — back off and retry; see Rate limits. |
| 500 | Unexpected server error — retry with idempotency care; contact support if persistent. |