# event-schema-missing

The request leaves out the **[schema](/learn/tutorials/first-steps-with-eventsourcingdb/registering-event-schemas)** to register.

- **Route:** `register-event-schema`
- **Description:** `event schema is missing: expected a JSON schema with type 'object'`
- **Details:** None; `details` is an empty object.

## Why It Happens

Registering a schema takes the event type in **`type`** and the JSON Schema in **`schema`**, and the request leaves out `schema`, for example because the client code had no schema at hand: in JavaScript, `JSON.stringify` leaves out a field whose value is `undefined`. A `schema` that is `null` or not a JSON object is rejected with `400 Bad Request` instead, since the body then does not have the shape the route expects.

The event type is checked first, so a request that lacks both is reported as **[`event-type-missing`](/docs/eventsourcingdb/errors/event-type-missing)**.

## How to Fix It

Send the schema in `schema`, as a JSON Schema with `"type": "object"` at its top level. Sending the same request again fails the same way, since the error depends on the request alone.

## Example

To register a schema for `io.eventsourcingdb.library.book-acquired` with a request that leaves out `schema`, 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-schema-missing",
    "description": "event schema is missing: expected a JSON schema with type 'object'",
    "details": {}
  }
}
```