Became follower – How to solve this OpenSearch exception

Opster Team

Aug-23, Version: 1-2.9

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Briefly, this error occurs when a node in the OpenSearch cluster loses its leader status and becomes a follower. This can happen due to network issues, resource constraints, or configuration problems. To resolve this, you can check the network connectivity between nodes, ensure there are sufficient resources (CPU, memory, disk space), and verify the cluster settings. If the issue persists, consider increasing the election timeout or adjusting the number of master-eligible nodes to maintain stability.

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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 OpenSearch concepts: cluster.

Log Context

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

 } else {
 assert newMode == Mode.FOLLOWER : newMode;
 joinTaskExecutor = null;
 .forEach(joinCallback -> joinCallback.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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