Failed execution of onLeaderFailure – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 8.5-8.9

Briefly, this error occurs when Elasticsearch encounters an issue while executing a task that requires leader node privileges. This could be due to network issues, node failures, or resource constraints. To resolve this, you can check the cluster health and ensure all nodes are properly connected. If a node is down, restart it. If the issue is due to resource constraints, consider scaling up your cluster or optimizing your indices to use less resources. Also, check your Elasticsearch logs for more specific information about the error.

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

Log Context

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


                    public void onFailure(Exception e2) {
                        logger.error("failed execution of onLeaderFailure"; e2);
                        assert false : e2;

                    public String toString() {


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