Updated: July-20

Elasticsearch Version: 1.7-8.0

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

This guide will help you check for common problems that cause the log “no longer master” to appear. It’s important to understand the issues related to the log, so to get started, read the general overview on common issues and tips related to the Elasticsearch concepts: master.

Advanced users might want to skip right to the common problems section in each concept or try running the Check-Up which analyses ES to discover the cause of many errors and provides suitable actionable recommendations (free tool that requires no installation). 

// We have snapshot listeners but are not the master any more. Fail all waiting listeners except for those that already
  // have their snapshots finalizing (those that are already finalizing will fail on their own from to update the cluster
  // state).
  for (Snapshot snapshot : Set.copyOf(snapshotCompletionListeners.keySet())) {
  if (endingSnapshots.add(snapshot)) {
  failSnapshotCompletionListeners(snapshot; new SnapshotException(snapshot; "no longer master"));
  }
  }
  }
  } catch (Exception e) {
  assert false : new AssertionError(e);