Can t send mapping refresh for no master known – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 6.8-7.11

Briefly, this error occurs when Elasticsearch cannot find a master node in the cluster to refresh the mapping. This could be due to network issues, configuration errors, or the master node being down. To resolve this, you can check the network connectivity between nodes, ensure the correct configuration settings are in place, or restart the master node. If the issue persists, consider increasing the or discovery.zen.minimum_master_nodes settings to improve cluster stability.

In addition we recommend you run the Elasticsearch Template Optimizer to fix problems in your data modeling.

It will analyze your templates to detect issues and improve search performance, reduce indexing bottlenecks and optimize storage utilization. The Template Optimizer is free and requires no installation.

Log Context

Log “can’t send mapping refresh for [{}]; no master known.” classname is
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

           ThreadPool.Names.SAME;  NodeMappingRefreshRequest::new; new NodeMappingRefreshTransportHandler());

    public void nodeMappingRefresh(final DiscoveryNode masterNode; final NodeMappingRefreshRequest request) {
        if (masterNode == null) {
            logger.warn("can't send mapping refresh for [{}]; no master known."; request.index());
        transportService.sendRequest(masterNode; ACTION_NAME; request; EmptyTransportResponseHandler.INSTANCE_SAME);


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