elastic/elasticsearch · error · IllegalArgumentException

no data stream actions specified, at least one must be speci

Error message

no data stream actions specified, at least one must be specified

What it means

IllegalArgumentException from the REST handler for _modify_data_streams when the parsed request carries a null or empty 'actions' list. The endpoint requires at least one action (add backing index, delete backing index, etc.) to do anything meaningful.

Source

Thrown at modules/data-streams/src/main/java/org/elasticsearch/datastreams/rest/RestModifyDataStreamsAction.java:64

    public List<Route> routes() {
        return List.of(new Route(POST, "/_data_stream/_modify"));
    }

    @Override
    protected RestChannelConsumer prepareRequest(RestRequest request, NodeClient client) throws IOException {
        ModifyDataStreamsAction.Request modifyDsRequest;
        try (XContentParser parser = request.contentParser()) {
            modifyDsRequest = ModifyDataStreamsAction.Request.PARSER.parse(
                parser,
                actions -> new ModifyDataStreamsAction.Request(
                    RestUtils.getMasterNodeTimeout(request),
                    RestUtils.getAckTimeout(request),
                    actions
                )
            );
        }
        if (modifyDsRequest.getActions() == null || modifyDsRequest.getActions().isEmpty()) {
            throw new IllegalArgumentException("no data stream actions specified, at least one must be specified");
        }
        boolean hasDeleteIndexAction = modifyDsRequest.getActions()
            .stream()
            .anyMatch(action -> action.getType() == DataStreamAction.Type.DELETE_BACKING_INDEX);
        if (hasDeleteIndexAction) {
            if (clusterSupportsFeature.test(DataStreamFeatures.DATA_STREAMS_MODIFY_DELETE_INDEX) == false) {
                throw new IllegalArgumentException("delete_backing_index is an unsupported action type for this mixed version cluster");
            }
        }
        return channel -> client.execute(ModifyDataStreamsAction.INSTANCE, modifyDsRequest, new RestToXContentListener<>(channel));
    }

    @Override
    public Set<String> supportedCapabilities() {
        return Set.of("data_streams.modify.delete_index");
    }
}

View on GitHub (pinned to db6a809a66)

Solutions

1. Supply at least one valid action object in the actions array (e.g. {"delete_backing_index":{"data_stream":"...","index":"..."}})
2. Validate the actions list is non-empty in the client before sending

Example fix

// before
POST _data_stream/_modify {"actions":[]}
// after
POST _data_stream/_modify
{"actions":[{"delete_backing_index":{"data_stream":"my-logs","index":".ds-my-logs-2024-12-31-000001"}}]}

// Client-side guard before sending the request:
if (actions == null || actions.isEmpty()) {
    throw new IllegalArgumentException("no data stream actions specified, at least one must be specified");
}

When it happens

Trigger: POST /_data_stream/_modify with a body like {"actions":[]} or with the actions field omitted entirely. The parser succeeds but the post-parse guard fails.

Common situations: Automation/template bug generating an empty actions array; client library serializing an empty list; testing the endpoint with a placeholder body.

Related errors

• Cannot create past TSDB backing index for data stream [{}] w
• data stream [{}] does not exist
• Elasticsearch version is missing from properties.
• Expected elasticsearch version to be numbers only of the for
• Invalid qualifier: ${qualifier}

AI-assisted analysis of elastic/elasticsearch@db6a809a66 (2026-08-12). Data as JSON: /api/errors/17b9fd6e22de4795. Report an issue: GitHub.