last-backed-up-event-missing

• 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 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 or 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:

{
  "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": {}
  }
}