Unassigned shards

Really need help on the unassigned-shard:

    "unassigned_info": { 
      "reason": "INDEX_REOPENED", 
      "details": null, 
      "allocation_status": "no_valid_shard_copy" 
    }, 
    "index": "<service_name>~<index_name>", 
    "shard": "4", 
    "state": "UNASSIGNED", 
    "node": null, 
    "shardSetName": "<service_name>~<index_name><shard#>" 
  }, 

  { 
    "primary": false, 
    "unassigned_info": { 
      "reason": "INDEX_REOPENED", 
      "details": null, 
      "allocation_status": "no_attempt" 
    }, 
    "index": "<service_name>~<index_name>", 
    "shard": "4", 
    "state": "UNASSIGNED", 
    "node": null, 
    "shardSetName": "<service_name>~<index_name><shard#>" 
  }, 

ES version: 5.6

Ask:
What tool can fix this?
What the root cause is?

Welcome to our community! :smiley:

This is very much EOL and you need to upgrade.

Are these primary shards?

Hey Mark,

Yes we will upgrade to later version, but for now this is the version we are using.

For the same shard#4, one is on primary and the other secondary. The only difference is the allocation_status is no_valid_shard_copy for the former, no_attempt for the latter.