How To Solve Issues Related to Log – Unexpected failure during

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Updated: Jan-20

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Troubleshooting Background       
Related Issues  
Log Context
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Troubleshooting background

To troubleshoot Elasticsearch log “Unexpected failure during” it’s important to understand common problems related to Elasticsearch concepts: admin, cluster. See detailed explanations below complete with common problems, examples and useful tips.

Cluster in Elasticsearch

What is it

In Elasticsearch a cluster is a collection of one or more nodes (servers / VMs). A cluster can consist of an unlimited number of nodes. The cluster provides interface for indexing and storing data and search capability across all of the data which is stored in the data nodes

Each cluster has a single master node that is elected by the master eligible nodes. In cases where the master is not available the other connected master eligible nodes elect a new master. Clusters are identified by a unique name, which defaults to “Elasticsearch”.


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 Fail To Assign Shards After Restart  

2Github Issue Number 38898  

Github Issue Number 23199


Log Context

Log ”Unexpected failure during [{}]” classname is TransportClusterHealthAction.java
We have extracted the following from Elasticsearch source code to get an in-depth context :

                         listener.onFailure(new NotMasterException("no longer master. source: [" + source + "]"));
                    }

                    
Override
                    public void onFailure(String source; Exception e) {
                        logger.error(() -> new ParameterizedMessage("unexpected failure during [{}]"; source); e);
                        listener.onFailure(e);
                    }
                });
            }
        } else {





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