action_request_validation_exception: action_request_validation_exception

What does it mean?

The request failed validation before execution. A required field is missing or fields are invalid, so Elasticsearch rejects the operation.

Why does it happen?

Missing required parameters (e.g. no index name specified), an empty body, an invalid combination of fields, or required information not supplied in a bulk/index request.

How to fix it

Review the list of missing/invalid fields in the error message and supply the required fields. Complete the request body and parameters according to the API documentation. In bulk requests, verify that each action line has correct metadata and a correct body.