Unknown error occurred while updating cluster state – How to solve this Elasticsearch error

Opster Team

July-20, Version: 1.7-8.0

Before you begin reading this guide, we recommend you try running the Elasticsearch Check-Up which can resolve issues that cause many errors.

This guide will help you check for common problems that cause the log ” Unknown error occurred while updating cluster state ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: cluster and plugin.

Advanced users might want to skip right to the common problems section in each concept or try running the Check-Up to analyze Elasticsearch configuration and help resolve this error.

Log Context

Log “Unknown error occurred while updating cluster state”classname  is TransportSetUpgradeModeAction.java We extracted the following from Elasticsearch source code for those seeking an in-depth context :

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) {
 logger.info("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
 if (tasksCustomMetadata == null || tasksCustomMetadata.tasks().isEmpty()) {


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