# ES 6.2.4 - ALLOCATION\_FAILED TranslogCorruptedException
**URL:** https://discuss.elastic.co/t/es-6-2-4-allocation-failed-translogcorruptedexception/142182
**Category:** Elasticsearch
**Created:** [July 30, 2018, 1:12pm UTC](https://discuss.elastic.co/t/es-6-2-4-allocation-failed-translogcorruptedexception/142182 "2018-07-30T13:12:27Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@ld\_pvl](https://discuss.elastic.co/u/ld_pvl)
#### Post date: [July 30, 2018, 1:12pm UTC](https://discuss.elastic.co/t/es-6-2-4-allocation-failed-translogcorruptedexception/142182/1 "2018-07-30T13:12:27Z")
Hi Elastic Team,
There's a single unassigned shard in the cluster due to ALLOCATION\_FAILED error which I can't figure out how to resolve.
I've already tried retrying several times using `curl -XPOST 'localhost:9200/_cluster/reroute?retry_failed=true&pretty'` and also bounced the node with the problematic shard shown in the output of `GET /_cluster/allocation/explain?pretty`:
```
"unassigned_info" : {
"reason" : "ALLOCATION_FAILED",
"at" : "2018-07-30T11:28:21.654Z",
"failed_allocation_attempts" : 5,
"details" : "failed shard on node [_wtZ2Gq7TvWoKsII2yCN6Q]: shard failure, reason [failed to recover from translog], failure EngineException[failed to recover from translog]; nested: TranslogCorruptedException[operation size must be at least 4 but was: 0]; ",
"last_allocation_status" : "no"
},
"can_allocate" : "no",
"allocate_explanation" : "cannot allocate because allocation is not permitted to any of the nodes that hold an in-sync shard copy",
...
other output
...
{
"node_id" : "_wtZ2Gq7TvWoKsII2yCN6Q",
"node_name" : "the_problematic_node",
"transport_address" : "171.134.100.215:9301",
"node_attributes" : {
"ml.machine_memory" : "270831382528",
"ml.max_open_jobs" : "20",
"ml.enabled" : "true",
"node.type" : "hot"
},
"node_decision" : "no",
"store" : {
"in_sync" : true,
"allocation_id" : "2ujCGOK-Swesr0sigjdeGw"
},
"deciders" : [
{
"decider" : "max_retry",
"decision" : "NO",
"explanation" : "shard has exceeded the maximum number of retries [5] on failed allocation attempts - manually call [/_cluster/reroute?retry_failed=true] to retry, [unassigned_info[[reason=ALLOCATION_FAILED], at[2018-07-30T11:28:21.654Z], failed_attempts[5], delayed=false, details[failed shard on node [_wtZ2Gq7TvWoKsII2yCN6Q]: shard failure, reason [failed to recover from translog], failure EngineException[failed to recover from translog]; nested: TranslogCorruptedException[operation size must be at least 4 but was: 0]; ], allocation_status[deciders_no]]]"
}
]
},
```
Is there a way to recover this shard?
Many thanks,
---
### Author:  [@ld\_pvl](https://discuss.elastic.co/u/ld_pvl)
#### Post date: [August 3, 2018, 1:35pm UTC](https://discuss.elastic.co/t/es-6-2-4-allocation-failed-translogcorruptedexception/142182/2 "2018-08-03T13:35:06Z")
After doing some further research into this, I think I've got myself a scrumptious translog corruption scenario here 😱. Probably worth mentioning here is the corruption happened probably because our hosts were abruptly rebooted on that day plus maybe the fact that we were not using the [recommended version of Java (1.8 u131)](https://www.elastic.co/guide/en/elasticsearch/reference/current/setup.html#jvm-version) - we were using a lower update version.
The problematic index's template is configured to have only two primary shards (no replicas). The unassigned shard is one of the two primary shards:
```
GET /_cat/shards/?h=index,shard,prirep,state,unassigned.reason
my_problematic_index 1 p UNASSIGNED ALLOCATION_FAILED
my_problematic_index 0 p STARTED
```
Therefore, I accepted fate and decided to "exterminate" shard 1 with data loss (at least I still got half of the data in that index left), following the steps of: [https://www.elastic.co/guide/en/elasticsearch/reference/current/cluster-reroute.html#\_forced\_allocation\_on\_unrecoverable\_errors](https://www.elastic.co/guide/en/elasticsearch/reference/current/cluster-reroute.html#_forced_allocation_on_unrecoverable_errors)
```
curl -X POST "localhost:9200/_cluster/reroute?pretty" -H 'Content-Type: application/json' -d'
{
"commands": [{
"allocate_empty_primary": {
"index": "my_problematic_index",
"shard": 1,
"node": "some_new_target_node_name",
"accept_data_loss": true
}
}]
}
```
P.S.: `allocate_stale_primary` did not work, therefore used `allocate_empty_primary`.
---
### Author:  [@system](https://discuss.elastic.co/u/system)
#### Post date: [August 31, 2018, 1:35pm UTC](https://discuss.elastic.co/t/es-6-2-4-allocation-failed-translogcorruptedexception/142182/3 "2018-08-31T13:35:17Z")
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