# last-backed-up-event-missing

The request leaves out **`lastBackedUpEvent`**, which is `null` for a full backup.

- **Route:** `create-backup`
- **Description:** `last backed up event is missing: expected the ID and hash of the event the previous backup ended at, or null for a full backup`
- **Details:** None; `details` is an empty object.

## Why It Happens

A **[backup](/docs/eventsourcingdb/backup-and-restore)** is either a **full backup** of the whole database or an **increment** with the events written after a previous backup. **`lastBackedUpEvent`** says which: `null` asks for a full backup, and the ID and hash of the event the previous backup ended at, as its `lastBackedUpEvent` item named them, ask for an increment. Without the field, EventSourcingDB does not guess, so that a client that has lost track of its previous backup does not get a full backup without noticing.

A typical cause is a request whose body is an empty object, `{}`. A `lastBackedUpEvent` that is there, but lacks its ID or its hash, is reported as **[`event-id-missing`](/docs/eventsourcingdb/errors/event-id-missing)** or **[`event-hash-missing`](/docs/eventsourcingdb/errors/event-hash-missing)** instead.

## How to Fix It

Send `"lastBackedUpEvent": null` for a full backup, or the `id` and `hash` from the `lastBackedUpEvent` item of the previous backup for an increment. Resending the request unchanged fails the same way.

## Example

For a request whose body is `{}`, 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/last-backed-up-event-missing",
    "description": "last backed up event is missing: expected the ID and hash of the event the previous backup ended at, or null for a full backup",
    "details": {}
  }
}
```