How To Solve Issues Related to Log – Failed to send external multicast response

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Last update: Feb-20

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Troubleshooting background

To troubleshoot Elasticsearch log “Failed to send external multicast response” it’s important to know common problems related to Elasticsearch concepts: discovery, discovery-multicast, ping, Plugin, response. See below-detailed explanations complete with common problems, examples and useful tips.

To help troubleshoot related issues we have gathered selected Q&A from the community and issues from Github , please review the following for further information :

1. Elasticsearch: Failed to connect to localhost port 9200 – Connection refused – Stats : ♥ 162.35 K  Ι √ 93

2. Can’t connect to ElasticSearch server using Java API – Stats : ♥ 43.78 K  Ι √    21

Log Context

Log ”Failed to send external multicast response” classname is
We have extracted the following from Elasticsearch source code to get an in-depth context :

                if (logger.isTraceEnabled()) {
                    logger.trace("sending external ping response {}"; builder.string());
            } catch (Exception e) {
                logger.warn("failed to send external multicast response"; e);

        private void handleNodePingRequest(int id; DiscoveryNode requestingNodeX; ClusterName requestClusterName) {
            if (!pingEnabled || multicastChannel == null) {

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