generated: '2026-07-20'
method: searched
source: https://docs.forum.market/api-reference/concepts/errors
format: custom-envelope
envelope:
  shape: '{ "error": { "code": string, "message": string, "details"?: object } }'
  code_field: error.code
  message_field: error.message
  validation_details: error.details.fields[]  # [{ field, message }] on 400 INVALID_PARAMETER
  note: >-
    Forum uses a custom JSON error envelope (NOT RFC 9457 problem+json). Use the
    machine-readable error.code for programmatic handling.
retry_guidance:
  retry: [429 RATE_LIMIT_EXCEEDED (after Retry-After), 500 INTERNAL_ERROR (exponential backoff)]
  do_not_retry: [400 (fix params), 401, 403 (check key/signature/permission), 404, 409 (resolve conflict)]
errors:
- http: 400
  code: INVALID_PARAMETER
  description: Request validation failed (see details.fields)
- http: 400
  code: INVALID_ORDER_TYPE
  description: Unsupported order type
- http: 400
  code: INVALID_SIDE
  description: Side must be buy or sell
- http: 400
  code: INVALID_QUANTITY
  description: Invalid order quantity
- http: 400
  code: INVALID_PRICE
  description: Invalid price value
- http: 400
  code: PRICE_BAND_VIOLATION
  description: Limit price is too far from current market price
- http: 400
  code: DUPLICATE_CLIENT_ORDER_ID
  description: Client order ID already in use (idempotency conflict)
- http: 401
  code: UNAUTHORIZED
  description: Missing or invalid authentication
- http: 401
  code: INVALID_SIGNATURE
  description: HMAC signature verification failed
- http: 401
  code: TIMESTAMP_EXPIRED
  description: Timestamp outside 30-second window
- http: 403
  code: INSUFFICIENT_PERMISSIONS
  description: API key lacks required permission (read vs trade)
- http: 404
  code: NOT_FOUND
  description: Resource not found
- http: 409
  code: INSUFFICIENT_MARGIN
  description: Insufficient margin for order
- http: 409
  code: REDUCE_ONLY_VIOLATION
  description: Reduce-only order would increase position
- http: 409
  code: ACCOUNT_LIQUIDATING
  description: Account is being liquidated
- http: 409
  code: ACCOUNT_REDUCE_ONLY
  description: Account is in reduce-only mode
- http: 409
  code: NO_LIQUIDITY
  description: No liquidity to fill order
- http: 409
  code: ORDER_NOT_CANCELLABLE
  description: Order already filled or cancelled
- http: 409
  code: POST_ONLY_WOULD_CROSS
  description: Post-only order would match immediately
- http: 409
  code: ENGINE_REJECTED
  description: Matching engine rejected the order
- http: 409
  code: EXCHANGE_IN_MAINTENANCE
  description: Exchange is in maintenance mode
- http: 429
  code: RATE_LIMIT_EXCEEDED
  description: Rate limit exceeded (see details.retryAfter and Retry-After header)
- http: 500
  code: INTERNAL_ERROR
  description: Unexpected server error
websocket_errors:
- code: UNKNOWN_COMMAND
  meaning: Unrecognized command
- code: AUTH_REQUIRED
  meaning: Private channel requires authentication
- code: RATE_LIMIT
  meaning: Message rate limit exceeded (connection will be closed)
- code: CONNECTION_LIMIT
  meaning: IP connection limit exceeded (connection will be closed)
- code: INVALID_SIGNATURE
  meaning: HMAC signature verification failed (WebSocket auth)
- code: MISSING_CREDENTIALS
  meaning: No authentication credentials provided