Fix error: Unable to parse response body

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 Error: Unable to parse response body 

This error occurs when Elasticsearch cannot process a response body, possibly due to incorrect formatting or syntax. To resolve this issue, make sure the response body is in the correct format (usually JSON) and that all syntax is correct.

If the error persists, start with these general steps:

• Check the Elasticsearch logs for more detailed error messages.
• Update Elasticsearch to the latest version.

If you're using the high-level Java REST client, continue to the next section.

This error can occur when the high-level Java REST client cannot parse the response received by the low-level Elasticsearch client.

The REST high-level client acts as a wrapper around the low-level client. The low-level client ultimately performs the HTTP request to the cluster. If the response returned to the high-level client is malformed or does not comply with the expected schema, the client throws the unable to parse response body exception.

Use the following sections to identify and fix the root cause of the error.

Elasticsearch does not guarantee compatibility between different major versions. Make sure the client version matches the Elasticsearch version. For more details, refer to the Elasticsearch Java server compatibility policy.

If your cluster is behind a reverse proxy and you have set a path prefix to access it, make sure to configure the high-level client to include the path prefix so the proxy routes the request to the cluster correctly.

For example, suppose you have an Nginx reverse proxy receiving connections at mycompany.com:80, and the /elasticsearch path prefix is set to proxy connections to a cluster running in your infrastructure. The /elasticsearch path prefix must be configured on the client you're using to access the cluster — not just on the host (mycompany.com).

Use setPathPrefix() to set the path prefix:

new RestHighLevelClient(
  RestClient.builder(
    new HttpHost("mycompany.com", 80, DEFAULT_SCHEME_NAME))
    .setPathPrefix("/elasticsearch")
);

For more context, refer to these Elastic community forum posts:

• RestHighLevelClient - Accessing an elastic http endpoint behind reverse proxy
• Issue with HighLevelRestClient with the host = xyz.com:8080/elasticsearch

The unable to parse response body error can occur when bulk indexing a large volume of data. By default, Elasticsearch has a maximum HTTP request body size of 100 MB. To raise this limit, increase the value of http.max_content_length in the Elasticsearch configuration file.

http.max_content_length: 200mb

For an example of an HTTP size limit issue, refer to this Elastic community forum post: Bulk indexing with java high level rest client gives error

If your Elasticsearch cluster runs on Kubernetes and is exposed through an ingress controller, check your ingress controller configuration. Misrouted or malformed responses from the controller can cause parsing errors in the client.

For an example of incorrect SSL redirection in an ingress controller, refer to this Elastic community forum post: RestHighLevelClient - Unable to parse response body