# Update Index Fact

> Update a single canonical deal fact — write a value directly or promote an existing observation — in the Lev API.

Source: https://www.lev.com/docs/build/index/update-fact

Last updated: 2026-09-16

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### `PATCH /api/external/v2/deals/{deal_id}/index/facts`

Update a single canonical deal fact value

#### Path Parameters

| Name | Type | Required | Description |
|------|------|----------|-------------|
| `deal_id` | `integer` | Yes | The deal ID |

#### Request Body

| Name | Type | Required | Description |
|------|------|----------|-------------|
| `sot_id` | `string` | Yes | Prefixed SOT id from a search result (e.g. d:5362, a:123:property:690). Identifies the fact to update. |
| `value` | `string` | No | Free-text replacement value. Provide exactly one of value or observation_id. |
| `observation_id` | `integer` | No | Observation id (> 0) to promote as the new canonical value. Returned by /index/observations. |

Response: `200`

#### Error Responses

- **422** (validation_error): Provide exactly one of value or observation_id; Metric is not editable
- **401** (unauthorized): Authentication required
- **404** (not_found): Deal not found
- **503** (service_unavailable): Deal fact update is temporarily unavailable. Please try again shortly.