## Transfer chat ownership

`POST /v1/chats/:chatId/owner`

Transfers ownership of a group chat to another participant. The new owner must already be a member of the chat.

## Parameters

| Parameter | Type | Required | Description |
|----------|-----|:-----:|---------|
| `chatId` (path) | number | yes | Chat ID (positive integer) |
| `format` (query) | string | no | `v2` turns on the v2 mode — see "The v2 mode" below. Any other value is ignored and the response is unchanged. A repeated `format` is not rejected: with `format=v1&format=v2` the last value wins, so the v2 mode is on, while `format=v2&format=v1` returns the legacy response. The bracket form `format[]=v2` turns on the v2 mode when all its values are `v2` |

## Request fields (body)

| Field | Type | Required | Description |
|------|-----|:-----:|---------|
| `userId` | number | yes | ID of the user to transfer ownership to. The user must be a participant in the chat. Participant list: `GET /v1/chats/:chatId/users` |

**The v2 mode.** `format=v2` transfers ownership through the v2 messenger, with the same body `{ "userId": … }` and the same response `true`. The Bitrix24 spelling `USER_ID`, other body fields and query parameters are rejected with `400 INVALID_PARAMS`. Before the transfer the API checks that the new owner is in the chat: a user who is not in the chat is rejected with `400 INVALID_PARAMS`, and ownership does not change.

## Examples

### curl — personal key

```bash
curl -X POST https://vibecode.bitrix24.com/v1/chats/456/owner \
  -H "X-Api-Key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{ "userId": 42 }'
```

### curl — OAuth application

```bash
curl -X POST https://vibecode.bitrix24.com/v1/chats/456/owner \
  -H "X-Api-Key: YOUR_APP_KEY" \
  -H "Authorization: Bearer USER_SESSION_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{ "userId": 42 }'
```

### JavaScript — personal key

```javascript
const res = await fetch('https://vibecode.bitrix24.com/v1/chats/456/owner', {
  method: 'POST',
  headers: {
    'X-Api-Key': 'YOUR_API_KEY',
    'Content-Type': 'application/json',
  },
  body: JSON.stringify({ userId: 42 }),
})

const { success, data } = await res.json()
```

### JavaScript — OAuth application

```javascript
const res = await fetch('https://vibecode.bitrix24.com/v1/chats/456/owner', {
  method: 'POST',
  headers: {
    'X-Api-Key': 'YOUR_APP_KEY',
    'Authorization': 'Bearer USER_SESSION_TOKEN',
    'Content-Type': 'application/json',
  },
  body: JSON.stringify({ userId: 42 }),
})

const { success, data } = await res.json()
```

### curl — the v2 mode

```bash
curl -X POST "https://vibecode.bitrix24.com/v1/chats/456/owner?format=v2" \
  -H "X-Api-Key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{ "userId": 42 }'
```

## Response fields

| Field | Type | Description |
|------|-----|---------|
| `success` | boolean | Always `true` on success |
| `data` | boolean | `true` when ownership was transferred successfully |

## Response example

```json
{
  "success": true,
  "data": true
}
```

## Error response example

422 — the ownership transfer condition was violated:

```json
{
  "success": false,
  "error": {
    "code": "BITRIX_ERROR",
    "message": "Change owner can only owner and user must be member in chat"
  }
}
```

## Errors

| HTTP | Code | Description |
|------|-----|---------|
| 400 | `INVALID_CHAT_ID` | `chatId` is not a positive integer — checked before the Bitrix24 call |
| 400 | `MISSING_PARAMS` | The `userId` field is missing or is not a positive integer |
| 400 | `INVALID_PARAMS` | The v2 mode only: a query parameter other than `format`, a body field other than `userId`, a body that is not a JSON object, or a `userId` outside the chat. Ownership does not change |
| 403 | `BITRIX_ACCESS_DENIED` | No permission to transfer ownership of this chat |
| 403 | `WRITE_BLOCKED_READONLY_KEY` | The key is read-only — see [access rights](/docs/access-rights) |
| 422 | `BITRIX_ERROR` | Only the current owner can transfer ownership, and the new owner must be a chat participant. In the v2 mode, it means Bitrix24 did not save the change; the portal code is in `error.b24Code` |
| 502 | `BITRIX_UNAVAILABLE` | Bitrix24 is unavailable or returned a server error |
| 403 | `SCOPE_DENIED` | The API key lacks the `im` scope |
| 401 | `TOKEN_MISSING` | The API key has no configured tokens |

Full list of common API errors — [Errors](/docs/errors).

## Known specifics

If the target user is not yet in the chat, add them via [`POST /v1/chats/:chatId/users`](/docs/chats/members/add) before calling this endpoint.

**Owner leaving the chat.** The chat creator remains the owner even after calling [`POST /v1/chats/:chatId/leave`](/docs/chats/management/leave) — leaving does not remove the owner status. To leave a chat completely: first transfer ownership to another participant with this endpoint, then call leave.

**The transfer cannot be undone by you.** The former owner stays in the chat, but only the new owner can give ownership back: a repeated call from the former owner gets `403 BITRIX_ACCESS_DENIED`.

## See also

- [Leave a chat](/docs/chats/management/leave)
- [Add members](/docs/chats/members/add)
- [Chat management](/docs/chats/management)