What causes "POST /_search response null" in apache/seatunnel?

Inspect how the RestClient is built — replace any custom wrapper or mock that can return null from performRequest

apache/seatunnel · error · ElasticsearchConnectorException

SEARCH_WITH_PIT_FAILED

SEARCH_WITH_PIT_FAILED

Error message

POST /_search response null

What it means

EsRestClient throws this when the low-level RestClient.performRequest returns null for a POST /_search request executed with a Point-in-Time context. Since a successful HTTP call never yields a null Response, this indicates an unexpected client/transport state, and the connector fails fast with SEARCH_WITH_PIT_FAILED.

Source

Thrown at seatunnel-connectors-v2/connector-elasticsearch/src/main/java/org/apache/seatunnel/connectors/seatunnel/elasticsearch/client/EsRestClient.java:1074

        // Add search_after if provided
        if (searchAfter != null && searchAfter.length > 0) {
            requestBody.put("search_after", searchAfter);
        }
        if (sliceMax != null && sliceMax > 1) {
            Map<String, Object> slice = new HashMap<>();
            slice.put("id", sliceId == null ? 0 : sliceId);
            slice.put("max", sliceMax);
            requestBody.put("slice", slice);
        }

        String endpoint = "/_search";
        Request request = new Request("POST", endpoint);
        request.setJsonEntity(JsonUtils.toJsonString(requestBody));

        try {
            Response response = restClient.performRequest(request);
            if (response == null) {
                throw new ElasticsearchConnectorException(
                        ElasticsearchConnectorErrorCode.SEARCH_WITH_PIT_FAILED,
                        "POST " + endpoint + " response null");
            }
            String entity = EntityUtils.toString(response.getEntity(), StandardCharsets.UTF_8);
            if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
                return parsePointInTimeResponse(entity, pitId);
            } else {
                throw new ElasticsearchConnectorException(
                        ElasticsearchConnectorErrorCode.SEARCH_WITH_PIT_FAILED,
                        String.format(
                                "POST %s response status code=%d, body=%s",
                                endpoint, response.getStatusLine().getStatusCode(), entity));
            }
        } catch (IOException ex) {
            throw new ElasticsearchConnectorException(
                    ElasticsearchConnectorErrorCode.SEARCH_WITH_PIT_FAILED, ex);
        }
    }

View on GitHub (pinned to cf67b549a7)

Solutions

Inspect how the RestClient is built — replace any custom wrapper or mock that can return null from performRequest
Enable debug logging on the ES RestClient to see the request lifecycle before the null response
Ensure the standard org.elasticsearch.client.RestClient is used without unusual interceptors that swallow responses

Defensive patterns

Strategy: try-catch

Validate before calling

// Ensure the RestClient is a real, started instance before searching:
Objects.requireNonNull(restClient, "RestClient must be initialized before PIT search");

Type guard

boolean hasResponse(Response r) { return r != null && r.getStatusLine() != null; }

Try / catch

try {
    result = esClient.searchWithPit(requestBody, pitId);
} catch (ElasticsearchConnectorException e) {
    if (String.valueOf(e.getMessage()).contains("response null")) {
        throw new IllegalStateException("RestClient returned null; check client init/interceptors", e);
    }
    throw e;
}

Prevention

Use the standard Elasticsearch RestClient without wrappers that can return null
Retry with backoff on transport anomalies
Fail fast at startup if the RestClient failed to initialize

When it happens

Trigger: Calling the PIT search method when the underlying RestClient returns null from performRequest — typically only in unusual transport or mocked-client situations.

Common situations: Custom or wrapped RestClient implementations (proxies, test doubles) that return null instead of throwing; edge cases in connection handling inside the ES Java client.

Understand the failure class

Background: "invalid response format", "malformed payload", "missing data field": when an API returns 200 but the response shape is wrong — this error's family across 23 libraries.

Related errors

AI-assisted analysis of apache/seatunnel@cf67b549a7 (2026-09-10). Data as JSON: /api/errors/7682ee5153e955a8. Report an issue: GitHub.