Cluster state update is NOT acknowledged – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 8-8.9

Briefly, this error occurs when a cluster state update request is not acknowledged by the required number of nodes within the specified timeout period. This could be due to network issues, heavy load on the cluster, or nodes being unresponsive. To resolve this, you can increase the timeout period for cluster state updates, ensure the cluster is not overloaded by optimizing queries or adding more nodes, and check the network connectivity between nodes. Also, ensure that the nodes are responsive and functioning properly.

This guide will help you check for common problems that cause the log ” Cluster state update is NOT acknowledged ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: plugin, cluster.

Log Context

Log “Cluster state update is NOT acknowledged” classname is
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

        ActionListener clusterStateUpdateListener = ActionListener.wrap(acknowledgedResponse -> {
            // State change was not acknowledged; we either timed out or ran into some exception
            // We should not continue and alert failure to the end user
            if (acknowledgedResponse.isAcknowledged() == false) {
      "Cluster state update is NOT acknowledged");
                wrappedListener.onFailure(new ElasticsearchTimeoutException("Unknown error occurred while updating cluster state"));

            // There are no tasks to worry about starting/stopping