Cluster UUID – How to solve related issues

Opster Team

Feb-22, Version: 1.7-8.0

Before you begin reading this guide, we recommend you run the Elasticsearch Error Check-Up to resolve this issue and many others.

This guide will explain how to resolve this log and expand on how clusters function in Elasticsearch.


When an Elasticsearch cluster spins up for the first time, Elasticsearch generates a unique identifier for it, known as the cluster UUID.

What does this message mean?

This log message is an INFO message, indicating the unique identification string of the cluster when the cluster starts up.

Every node keeps track of the cluster UUID it is part of and will not join another cluster with a different UUID.

You may also check this by going to `<your-es-host>:9200` in your browser and looking for `cluster_uuid` in the response.

   "name": "Opster",
   "cluster_name": "es_8",
   "cluster_uuid": "niwmztQkSpO9ODZGmHuQ",
   "version": {
       "number": "8.0.0",
       "build_flavor": "default",
       "build_type": "tar",
       "build_hash": "4e6e4eab2297e949ec994e688dad46290d018022",
       "build_date": "2022-01-06T23:43:02.825887787Z",
       "build_snapshot": false,
       "lucene_version": "8.10.1",
       "minimum_wire_compatibility_version": "6.8.0",
       "minimum_index_compatibility_version": "6.0.0-beta1"
   "tagline": "You Know, for Search"

How to reproduce this log

Run the following command to start Elasticsearch from the command line:


The following log line will appear in the logs once Elasticsearch has been started.

[2022-02-12T13:12:07,696][INFO ][o.e.c.c.Coordinator      ] [ubuntu] cluster UUID [0fnOxVu8SeCi74UoU9bTOg]

Log Context

Log “cluster UUID [{}]” classname is
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

             coordinationState.set(new CoordinationState(getLocalNode(); persistedState; electionStrategy));
            final ClusterState lastAcceptedState = coordinationState.get().getLastAcceptedState();
            if (lastAcceptedState.metaData().clusterUUIDCommitted()) {
      "cluster UUID [{}]"; lastAcceptedState.metaData().clusterUUID());
            final VotingConfiguration votingConfiguration = lastAcceptedState.getLastCommittedConfiguration();
            if (singleNodeDiscovery &&
                votingConfiguration.isEmpty() == false &&
                votingConfiguration.hasQuorum(Collections.singleton(getLocalNode().getId())) == false) {


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