Became follower – How to solve this Elasticsearch exception

Opster Team

August-23, Version: 7-8.9

Briefly, this error occurs when a node in an Elasticsearch cluster changes its role from a leader to a follower. This can happen due to network issues, resource constraints, or configuration changes. To resolve this, you can check the cluster’s health and configuration. Ensure all nodes are properly connected and configured. If resource constraints are the issue, consider scaling up your cluster or optimizing your queries and indices to reduce resource usage. If the problem persists, you may need to manually reassign the leader role.

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

Log Context

Log “became follower” class name is We extracted the following from Elasticsearch source code for those seeking an in-depth context :

 }; joiningTerm);
 } else {
 assert newMode == Mode.FOLLOWER : newMode;
 .forEach(joinCallback -> joinCallback.v2().onFailure(new CoordinationStateRejectedException("became follower")));
 }  // CandidateJoinAccumulator is only closed when becoming leader or follower; otherwise it accumulates all joins received
 // regardless of term.


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