## Set the "unread" mark

`POST /v1/chats/:dialogId/unread`

Sets the "unread" mark on the chat's row in the recent dialog list — the mark the messenger shows after the "Mark as unread" command. The mark is independent of the unread message counter: it neither marks messages as read nor makes them unread.

## Parameters

| Parameter | Type | Required | Default | Description |
|----------|-----|:-----:|-----------|---------|
| `dialogId` (path) | string | yes | — | Dialog ID: `chatXXX` for a group chat, a user ID for a direct dialog, or the `me` alias. Dialog list — [Recent dialogs](/docs/chats/discovery/recent) |

There are no query parameters and no body fields. Any query parameter or body field is rejected with `400 INVALID_PARAMS`.

## Examples

### curl — personal key

```bash
curl -X POST "https://vibecode.bitrix24.com/v1/chats/chat123/unread" \
  -H "X-Api-Key: YOUR_API_KEY"
```

### curl — OAuth application

```bash
curl -X POST "https://vibecode.bitrix24.com/v1/chats/chat123/unread" \
  -H "X-Api-Key: YOUR_APP_KEY" \
  -H "Authorization: Bearer USER_SESSION_TOKEN"
```

### JavaScript — personal key

```javascript
const res = await fetch('https://vibecode.bitrix24.com/v1/chats/chat123/unread', {
  method: 'POST',
  headers: { 'X-Api-Key': 'YOUR_API_KEY' },
})

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

### JavaScript — OAuth application

```javascript
const res = await fetch('https://vibecode.bitrix24.com/v1/chats/chat123/unread', {
  method: 'POST',
  headers: {
    'X-Api-Key': 'YOUR_APP_KEY',
    'Authorization': 'Bearer USER_SESSION_TOKEN',
  },
})

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

## Response fields

| Field | Type | Description |
|------|-----|---------|
| `success` | boolean | Always `true` on success |
| `data.result` | boolean | Always `true`, see "Known specifics" |

## Response example

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

## Error response example

400 — a body field was sent:

```json
{
  "success": false,
  "error": {
    "code": "INVALID_PARAMS",
    "message": "Body field `unread` is not accepted by POST /v1/chats/:dialogId/unread. It takes no body fields."
  }
}
```

## Errors

| HTTP | Code | Description |
|------|-----|---------|
| 400 | `INVALID_PARAMS` | A query parameter or a body field was sent, or the body is not a JSON object. Checked before any call to Bitrix24 |
| 403 | `SCOPE_DENIED` | The API key does not have the `im` scope |
| 403 | `WRITE_BLOCKED_READONLY_KEY` | The key is read-only — the call changes the chat state. Rejected before any call to Bitrix24 |
| 401 | `TOKEN_MISSING` | The API key has no Bitrix24 tokens configured |
| 404 | `ENTITY_NOT_FOUND` | Bitrix24 answered "not found"; the portal code is in `error.b24Code` |
| 422 | `BITRIX_ERROR` | Bitrix24 returned an error; the portal code is in `error.b24Code`. A chat that does not exist — `CHAT_NOT_FOUND` |
| 502 | `ME_ALIAS_RESOLUTION_FAILED` | Failed to resolve the user when using the `me` alias |
| 502 | `BITRIX_UNAVAILABLE` | Bitrix24 is unavailable or returned a server error |

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

## Known specifics

- **The call does not report whether the mark was set.** The response `data.result: true` arrives regardless of the outcome: when the chat is not in the current user's recent dialog list — for example, the chat was hidden from the list — the mark is not set, but the response is the same. To check the result, read the `unread` field of the chat's row in the [recent dialog list](/docs/chats/discovery/recent) in the v2 mode or `isMarkedAsUnread` in the [counters](/docs/chats/discovery/counters).
- **A repeated call on a marked chat changes nothing:** the "[read later](/docs/chats/messages/mark)" pointer, if set, stays where it was.

## See also

- [Clear the "unread" mark](/docs/chats/management/unread-delete)
- [Read later](/docs/chats/messages/mark)
- [Mark as read](/docs/chats/messages/read)
- [Unread counters](/docs/chats/discovery/counters)
- [Chat management](/docs/chats/management)