Failed to notify ClusterStateApplier – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 6.8-6.8

Briefly, this error occurs when Elasticsearch is unable to notify the ClusterStateApplier about changes in the cluster state. This could be due to network issues, node failures, or resource constraints. To resolve this issue, you can try the following: 1) Check the network connectivity between the nodes. 2) Verify the health of the nodes in the cluster. 3) Check if the system resources like CPU, memory, and disk space are sufficient. 4) Review the Elasticsearch logs for more detailed error messages that can help identify the root cause.

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

Log Context

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

        clusterStateAppliers.forEach(applier -> {
            try {
                logger.trace("calling [{}] with change to version [{}]"; applier; clusterChangedEvent.state().version());
            } catch (Exception ex) {
                logger.warn("failed to notify ClusterStateApplier"; ex);

    private void callClusterStateListeners(ClusterChangedEvent clusterChangedEvent) {


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