elastic/elasticsearch · error · IllegalArgumentException

Required one of fields {}, but none were specified.

Error message

Required one of fields {}, but none were specified.

What it means

Thrown by throwMissingRequiredFields after the ObjectParser finishes consuming all fields and discovers that at least one declared required-field set has zero members present in the input. A required-field set is registered via declareRequiredFieldSet and mandates that at least one field from the set appear in every valid document.

Source

Thrown at libs/x-content/src/main/java/org/elasticsearch/xcontent/ObjectParser.java:342

        if (requiredFields != null && requiredFields.isEmpty() == false) {
            throwMissingRequiredFields(requiredFields);
        }
        return value;
    }

    private void throwExpectedStartObject(XContentParser parser, XContentParser.Token token) {
        throw new XContentParseException(parser.getTokenLocation(), "[" + name + "] Expected START_OBJECT but was: " + token);
    }

    private static void throwMissingRequiredFields(List<String[]> requiredFields) {
        final StringBuilder message = new StringBuilder();
        for (int i = 0; i < requiredFields.size(); i++) {
            if (i > 0) {
                message.append(" ");
            }
            message.append("Required one of fields ").append(Arrays.toString(requiredFields.get(i))).append(", but none were specified.");
        }
        throw new IllegalArgumentException(message.toString());
    }

    private static void ensureExclusiveFields(List<List<String>> exclusiveFields) {
        StringBuilder message = null;
        for (List<String> fieldset : exclusiveFields) {
            if (fieldset.size() > 1) {
                if (message == null) {
                    message = new StringBuilder();
                }
                message.append("The following fields are not allowed together: ").append(fieldset).append(" ");
            }
        }
        if (message != null && message.length() > 0) {
            throw new IllegalArgumentException(message.toString());
        }
    }

    private void maybeMarkExclusiveField(String currentFieldName, List<List<String>> exclusiveFields) {

View on GitHub (pinned to db6a809a66)

Solutions

1. Read the error message to see which field set is required and add at least one field from that set.
2. Check the API documentation for required fields on the endpoint you are calling.
3. Use the endpoint's schema or OpenAPI spec to discover required field groups.
4. If the field group should not be required, verify the ObjectParser configuration in the server code.

Example fix

// before — missing required field
PUT /my-index
{
  "mappings": { "properties": { "name": { "type": "text" } } }
}

// after — required field included (if the parser required it)
PUT /my-index
{
  "settings": { "number_of_shards": 1 },
  "mappings": { "properties": { "name": { "type": "text" } } }
}

// Before sending, check that at least one field from each required set is present
List<Set<String>> requiredSets = List.of(Set.of("number_of_shards", "number_of_replicas"));
for (Set<String> required : requiredSets) {
    if (required.stream().noneMatch(body::containsKey)) {
        throw new IllegalArgumentException("Missing required field from: " + required);
    }
}

try {
    objectParser.parse(parser, context);
} catch (IllegalArgumentException e) {
    if (e.getMessage().contains("Required one of fields")) {
        return badRequest(e.getMessage());
    }
    throw e;
}

When it happens

Trigger: Sending a request body to an endpoint whose ObjectParser declared required field sets (via declareRequiredFieldSet) but omitting every field from at least one of those sets. For example, a settings update that requires at least one of ["number_of_shards", "number_of_replicas"] but provides neither.

Common situations: Omitting a mandatory field group from an index creation or settings update request. Copying a partial template from documentation that does not include the required field. Assuming a field is optional when the parser marks it as required.

Related errors

• The following fields are not allowed together: {}
• [{}] Expected START_OBJECT but was: {}
• [{}] failed to parse object
• [{}] doesn't support arrays. Use a single object with multip
• [{}] failed to parse field [{}]

AI-assisted analysis of elastic/elasticsearch@db6a809a66 (2026-08-12). Data as JSON: /api/errors/22d283ba5206ac36. Report an issue: GitHub.