# order-unknown

The **order** of a read is neither `chronological` nor `antichronological`.

- **Route:** `read-events`
- **Description:** `order is unknown: expected 'chronological' or 'antichronological'`
- **Details:** **`value`**, the order as the request gave it.

## Why It Happens

The option **`order`** of a read takes exactly two values: `chronological`, which reads the oldest event first, and `antichronological`, which **[reads the newest event first](/learn/tutorials/first-steps-with-eventsourcingdb/reading-events#reading-in-reverse-order)**. The values are **case-sensitive**, so `Chronological` is refused, and so are an empty string and words from other APIs, such as `asc`, `desc`, or `reverse`.

Leaving out `order` is fine, and reads chronologically. Observing events has no order, so `observe-events` does not know the option at all, and refuses it with `400 Bad Request` as an unknown field.

## How to Fix It

Send `order` as `chronological` or `antichronological`, in lowercase, or leave it out to read chronologically. Sending the same request again fails the same way, since the outcome depends on the request alone.

## Example

To read the events of `/books/42` with the order `descending`, EventSourcingDB answers with this error, as a line of the stream, and then ends the stream with its `end` item:

```json
{
  "type": "error",
  "data": {
    "code": "https://docs.eventsourcingdb.io/errors/order-unknown",
    "description": "order is unknown: expected 'chronological' or 'antichronological'",
    "details": {
      "value": "descending"
    }
  }
}
```