# event-id-malformed

An **event ID** in the request is **not a non-negative integer written without a sign or a leading zero**.

- **Routes:** `write-events`, `read-events`, `observe-events`, `audit-history`, and `create-backup`
- **Description:** `event ID is malformed: expected a non-negative integer of at most 9223372036854775807 in a string, such as '42'`
- **Details:** **`value`**, the ID as the request gave it. When reading or observing events, also **`bound`**, the bound it belongs to, `lowerBound` or `upperBound`. When writing events, also **`precondition`**, the place of the precondition in its list, counting from 0.

## Why It Happens

An event ID is an **integer from 0 to 9223372036854775807, written as a string of digits without a sign or a leading zero**, such as `"42"`. The database reports this error for an ID that **cannot be read as an integer**, such as `"4.2"` or `"latest"`, that is **negative**, such as `"-1"`, that is **written with a sign, a leading zero, or white space**, such as `"+5"`, `"007"`, or `" 5"`, or that is **larger than 9223372036854775807**. It concerns the same IDs as **[`event-id-missing`](/docs/eventsourcingdb/errors/event-id-missing)**: the **[bounds](/learn/tutorials/first-steps-with-eventsourcingdb/reading-events#reading-a-specific-range)** of a read or an observation, the `eventId` of an `isSubjectOnEventId` **[precondition](/docs/eventsourcingdb/preconditions)**, and the `id` in `lastAuditedEvent` or `lastBackedUpEvent`. An ID sent as a JSON number, such as `42`, does not get this far: the database rejects the request with **`400 Bad Request`**.

A typical cause is a lower bound of `"-1"`, meant to read from before the first event, which has the ID `0`.

## How to Fix It

Send the ID as a string of digits without a sign or a leading zero, as the database writes it, such as `"42"`. To read from the first event, leave out the lower bound, or make it `"0"` and inclusive. Sending the same request again fails the same way, since the error depends on the request alone.

## Example

To read the events of `/books/42` with a `lowerBound` whose ID is `-1`, 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/event-id-malformed",
    "description": "event ID is malformed: expected a non-negative integer of at most 9223372036854775807 in a string, such as '42'",
    "details": {
      "bound": "lowerBound",
      "value": "-1"
    }
  }
}
```