> ## Documentation Index
> Fetch the complete documentation index at: https://developer.buildmarkets.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Order Cancel Reject <9>

> How the gateway notifies clients when a cancellation request cannot be processed, and how to handle the rejection.

## Overview

The Order Cancel Reject message (MsgType = `"9"`) is sent by the gateway when a cancellation request cannot be processed. This typically occurs when an order is already filled, expired, or in a non-cancellable state.

## Field Layout

| Tag | Field            | Description                                      | Required | Type   | Values                   |
| --- | ---------------- | ------------------------------------------------ | -------- | ------ | ------------------------ |
| 11  | ClOrdID          | Identifier of the cancel request                 | Y        | String |                          |
| 17  | ExecId           | Execution ID assigned by the gateway             | Y        | String |                          |
| 37  | OrderId          | OrderId assigned by the gateway                  | Y        | String |                          |
| 39  | OrdStatus        | Current order status                             | Y        | Char   | `8`=Rejected             |
| 41  | OrigClOrdID      | ClOrdID of the order that could not be cancelled | Y        | String |                          |
| 58  | Text             | Reason for rejection (free text)                 | N        | String |                          |
| 434 | CxlRejResponseTo | Type of request being rejected                   | Y        | Int    | `1`=Order Cancel Request |

## Example Message

```
8=FIX.4.4|35=9|49=BUILDMARKETS|56=CLIENT1|11=CXL-20260212-001|17=EXEC-020|37=BMKT-78450|39=8|41=ORD-20260212-001|434=1|58=Order already filled|10=056|
```

## Handling Cancel Rejects

1. Review Tag 58 (Text) for the human-readable rejection reason
2. The original order maintains its current state — use Order Status Request to verify if needed
3. Common rejection causes: order already filled, order already cancelled, order expired, or invalid OrderId

## REST Equivalent

The REST cancel endpoint (`POST /api/external/cancel`) provides similar functionality, returning error details when cancellation fails.