Health check failed – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 7.9-8.9

Briefly, this error occurs when Elasticsearch is unable to perform its routine health check, which could be due to various reasons such as network issues, insufficient resources, or configuration problems. To resolve this issue, you can try the following: 1) Check the Elasticsearch logs for more detailed error messages. 2) Verify the network connectivity between your application and Elasticsearch. 3) Ensure that Elasticsearch has sufficient resources (CPU, memory, disk space). 4) Check your Elasticsearch configuration for any errors or inconsistencies.

This guide will help you check for common problems that cause the log ” health check failed ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: monitor.

Log Context

Log “health check failed” classname is
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

        private final byte[] bytesToWrite = UUIDs.randomBase64UUID().getBytes(StandardCharsets.UTF_8);

        public void onFailure(Exception e) {
            logger.error("health check failed"; e);

        public void onRejection(Exception e) {
            if (e instanceof EsRejectedExecutionException esre && esre.isExecutorShutdown()) {


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