# Elasticsearch Java Client throws Exception when deserialize hotThreads response **URL:** \ **Category:** Elasticsearch\ **Tags:** language-clients\ **Created:** [August 19, 2024, 2:06pm UTC](https://discuss.elastic.co/t/elasticsearch-java-client-throws-exception-when-deserialize-hotthreads-response/365144 "2024-08-19T14:06:29Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![corojoon93](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/corojoon93/32/136894_2.png) [@corojoon93](https://discuss.elastic.co/u/corojoon93)\ **Post date:** [August 19, 2024, 2:06pm UTC](https://discuss.elastic.co/t/elasticsearch-java-client-throws-exception-when-deserialize-hotthreads-response/365144/1 "2024-08-19T14:06:29Z")
I used "co.elastic.clients:elasticsearch-java:8.15.0", "org.springframework.boot:3.2.7" And this is my Java code. ```auto @Service @RequiredArgsConstructor public class NodeHealthService { private final ElasticsearchClient elasticsearchClient; public HotThreadsResponse hotThreads() throws Exception { return elasticsearchClient.nodes().hotThreads(); } } ``` This code throws TransportException when deserialize response. co.elastic.clients.transport.TransportException: node: [https://xxxxx/](https://xxxxx/), status: 200, [es/nodes.hot\_threads] Expecting JSON data but response content-type is: text/plain; charset=UTF-8 The ElasticsearchClient configuration code is as follows: ```auto @Configuration public class ElasticJavaClientConfig { private final static int ES_CONNECTION_TIMEOUT = 5000; private final static int ES_SOCKET_TIMEOUT = 60000; @Bean public RestClient restClient(ElasticsearchInfoProperty elasticsearchInfoProperty) { final URI uri = URI.create(elasticsearchInfoProperty.url()); final String protocol = uri.getScheme(); final String host = uri.getHost(); final int port = uri.getPort(); final String username = elasticsearchInfoProperty.username(); final String password = elasticsearchInfoProperty.password(); final CredentialsProvider credentialsProvider = new BasicCredentialsProvider(); credentialsProvider.setCredentials( AuthScope.ANY, new UsernamePasswordCredentials(username, password)); HttpHost httpHost = new HttpHost(host, port, protocol); List
requestHeaders = RequestOptions.DEFAULT.toBuilder() .addHeader(org.springframework.http.HttpHeaders.HOST, host) .build() .getHeaders(); return RestClient.builder(httpHost) .setDefaultHeaders(requestHeaders.toArray(new Header[]{})) .setHttpClientConfigCallback( httpClientBuilder -> { httpClientBuilder.disableAuthCaching(); httpClientBuilder.setKeepAliveStrategy((httpResponse, httpContext) -> 300); return httpClientBuilder.setDefaultCredentialsProvider(credentialsProvider); }) .setRequestConfigCallback( requestConfigBuilder -> requestConfigBuilder .setConnectTimeout(ES_CONNECTION_TIMEOUT) .setSocketTimeout(ES_SOCKET_TIMEOUT)).build(); } @Bean public ElasticsearchClient elasticsearchClient(RestClient restClient) { ElasticsearchTransport transport = new RestClientTransport(restClient, new SimpleJsonpMapper()); return new ElasticsearchClient(transport); } } ``` What should I do to make it work properly? ---
**Author:** ![dadoonet](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/dadoonet/32/137187_2.png) [@dadoonet](https://discuss.elastic.co/u/dadoonet)\ **Post date:** [August 19, 2024, 2:54pm UTC](https://discuss.elastic.co/t/elasticsearch-java-client-throws-exception-when-deserialize-hotthreads-response/365144/2 "2024-08-19T14:54:02Z")
Welcome @corojoon93 Thanks for reporting. That's a bug I can reproduce. I opened: > > > \### Java API client version > > 8.15.0 > > \### Java version > > 21.0 > > \### Elasticsearch V…ersion > > 8.15.0 > > \### Problem description > > With the 8.15.0 client, run: > > \`\`\`java > HotThreadsResponse hotThreadsResponse = client.nodes().hotThreads(); > \`\`\` > > This gives: > > \`\`\` > co.elastic.clients.transport.TransportException: node: https://localhost:63624/, status: 200, \[es/nodes.hot\_threads\] Expecting JSON data but response content-type is: text/plain; charset=UTF-8 > > at co.elastic.clients.transport.ElasticsearchTransportBase.checkJsonContentType(ElasticsearchTransportBase.java:471) > at co.elastic.clients.transport.ElasticsearchTransportBase.decodeTransportResponse(ElasticsearchTransportBase.java:394) > at co.elastic.clients.transport.ElasticsearchTransportBase.getApiResponse(ElasticsearchTransportBase.java:363) > at co.elastic.clients.transport.ElasticsearchTransportBase.performRequest(ElasticsearchTransportBase.java:147) > at co.elastic.clients.elasticsearch.nodes.ElasticsearchNodesClient.hotThreads(ElasticsearchNodesClient.java:199) > at fr.pilato.test.elasticsearch.hlclient.EsClientIT.callHotThreads(EsClientIT.java:956) > at java.base/java.lang.reflect.Method.invoke(Method.java:580) > at java.base/java.util.ArrayList.forEach(ArrayList.java:1596) > at java.base/java.util.ArrayList.forEach(ArrayList.java:1596) > \`\`\` ---
**Author:** ![swallez](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/swallez/32/11972_2.png) [@swallez](https://discuss.elastic.co/u/swallez)\ **Post date:** [August 19, 2024, 3:44pm UTC](https://discuss.elastic.co/t/elasticsearch-java-client-throws-exception-when-deserialize-hotthreads-response/365144/3 "2024-08-19T15:44:55Z")
This API does not return JSON but a result in text format. The Java client tries to parse it as JSON, which fails. We will update this in a future release. The workaround is to call `/_nodes/hot_threads` with the `RestClient`. ---
**Author:** ![corojoon93](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/corojoon93/32/136894_2.png) [@corojoon93](https://discuss.elastic.co/u/corojoon93)\ **Post date:** [August 20, 2024, 12:56am UTC](https://discuss.elastic.co/t/elasticsearch-java-client-throws-exception-when-deserialize-hotthreads-response/365144/4 "2024-08-20T00:56:09Z")
thank you for your help! ---
**Author:** ![Quentin\_Pradet](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/quentin_pradet/32/94192_2.png) [@Quentin\_Pradet](https://discuss.elastic.co/u/Quentin_Pradet)\ **Post date:** [August 20, 2024, 6:15pm UTC](https://discuss.elastic.co/t/elasticsearch-java-client-throws-exception-when-deserialize-hotthreads-response/365144/5 "2024-08-20T18:15:37Z")
We fixed the specification in [Fix hot threads to always return strings by pquentin · Pull Request #2793 · elastic/elasticsearch-specification · GitHub](https://github.com/elastic/elasticsearch-specification/pull/2793), so it should be in the next version of the Java client (and all other clients). ---
**Author:** ![dadoonet](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/dadoonet/32/137187_2.png) [@dadoonet](https://discuss.elastic.co/u/dadoonet)\ **Post date:** [January 12, 2026, 2:13pm UTC](https://discuss.elastic.co/t/elasticsearch-java-client-throws-exception-when-deserialize-hotthreads-response/365144/6 "2026-01-12T14:13:16Z")
This should finally land in 9.3, thanks to @ltrotta😉 > > > Using the new \`response\_media\_type\` Request property introduced in the spec with… https://github.com/elastic/elasticsearch-specification/pull/5779 to correctly handle endpoints that return text/plain, including HotThreads. > > Fixes https://github.com/elastic/elasticsearch-java/issues/865.