Cancel Order - Notional Protocol

HyperliquidPolymarket

Cancels one or more orders by Notional order ID. Use the exchange signing flow with the account owner or an approved API wallet. The stored order determines the market and ownership; a is a compatibility selector. Duplicate order IDs within one cancel batch are rejected.

Endpoint

POST /exchange

Request Body

Parameter	Type	Description
`action`*	object	Cancel payload
`nonce`*	number	Replay-protection nonce, e.g., `1701234567890`
`expiresAfter`	number	Optional expiration timestamp in ms, e.g., `1701234627890`
`signature`*	object	EIP-712 signature

action

Field	Type	Description
`type`*	string	Must be `"cancel"`
`cancels`*	array	One or more cancel items

action.cancels[]

Field	Type	Description
`a`*	string \| number	Compatibility asset selector, e.g., `"00020000"`
`o`*	string	Notional order ID, e.g., `"0x1a2b3c..."`

Response

200: Confirmed
200: Pending
200: Rejected

{
  "status": "ok",
  "response": {
    "type": "cancel",
    "data": {
      "statuses": [
        {
          "success": true
        }
      ]
    }
  },
  "metadata": {
    "results": [
      {
        "oid": "0x1a2b3c...",
        "status": "confirmed",
        "orderId": "0x1a2b3c..."
      }
    ]
  }
}

{
  "status": "ok",
  "response": {
    "type": "cancel",
    "data": {
      "statuses": [
        {
          "pending": {
            "cloid": "0x1a2b3c..."
          }
        }
      ]
    }
  },
  "metadata": {
    "results": [
      {
        "oid": "0x1a2b3c...",
        "status": "pending",
        "orderId": "0x1a2b3c..."
      }
    ]
  }
}

{
  "status": "ok",
  "response": {
    "type": "cancel",
    "data": {
      "statuses": [
        {
          "error": "Order was never placed, already canceled, or filled"
        }
      ]
    }
  },
  "metadata": {
    "results": [
      {
        "oid": "0x1a2b3c...",
        "status": "not_found",
        "orderId": "0x1a2b3c...",
        "error": "Order was never placed, already canceled, or filled"
      }
    ]
  }
}

Status Variants

Variant	Fields	Meaning
`success`	`true`	Exchange confirmed the cancel
`pending`	`cloid`	Final venue confirmation is not yet available
`error`	Error message	Validation or exchange failure

metadata.results[].status may be confirmed, failed, pending, rejected, not_found, no_venue_id, or invalid_state. Cancel requests reject reused nonces, including an identical retry. After an uncertain response, check current order state before signing another cancel with a new nonce.