---
title: Circuit breaker errors
description: Elasticsearch uses circuit breakers to prevent nodes from running out of JVM heap memory. If Elasticsearch estimates an operation would exceed a circuit...
url: https://docs-v3-preview.elastic.dev/elastic/docs-content/pull/4236/troubleshoot/elasticsearch/circuit-breaker-errors
products:
  - Elasticsearch
---

# Circuit breaker errors
Elasticsearch uses [circuit breakers](https://docs-v3-preview.elastic.dev/elastic/elasticsearch/tree/main/reference/elasticsearch/configuration-reference/circuit-breaker-settings) to prevent nodes from running out of JVM heap memory. If Elasticsearch estimates an operation would exceed a circuit breaker, it stops the operation and returns an error.
By default, the [parent circuit breaker](https://docs-v3-preview.elastic.dev/elastic/elasticsearch/tree/main/reference/elasticsearch/configuration-reference/circuit-breaker-settings#parent-circuit-breaker) triggers at 95% JVM memory usage. To prevent errors, we recommend taking steps to reduce memory pressure if usage consistently exceeds 85%.
See [this video](https://www.youtube.com/watch?v=k3wYlRVbMSw) for a walkthrough of diagnosing circuit breaker errors.
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## Diagnose circuit breaker errors

**Error messages**
If a request triggers a circuit breaker, Elasticsearch returns an error with a `429` HTTP status code.
```js
{
  'error': {
    'type': 'circuit_breaking_exception',
    'reason': '[parent] Data too large, data for [<http_request>] would be [123848638/118.1mb], which is larger than the limit of [123273216/117.5mb], real usage: [120182112/114.6mb], new bytes reserved: [3666526/3.4mb]',
    'bytes_wanted': 123848638,
    'bytes_limit': 123273216,
    'durability': 'TRANSIENT'
  },
  'status': 429
}
```

Elasticsearch also writes circuit breaker errors to [`elasticsearch.log`](https://docs-v3-preview.elastic.dev/elastic/docs-content/pull/4236/deploy-manage/monitor/logging-configuration/elasticsearch-log4j-configuration-self-managed). This is helpful when automated processes, such as allocation, trigger a circuit breaker.
```txt
Caused by: org.elasticsearch.common.breaker.CircuitBreakingException: [parent] Data too large, data for [<transport_request>] would be [num/numGB], which is larger than the limit of [num/numGB], usages [request=0/0b, fielddata=num/numKB, in_flight_requests=num/numGB, accounting=num/numGB]
```

**Check JVM memory usage**
If you’ve enabled Stack Monitoring, you can view JVM memory usage in Kibana. In the main menu, click **Stack Monitoring**. On the Stack Monitoring **Overview** page, click **Nodes**. The **JVM Heap** column lists the current memory usage for each node.
You can also use the [cat nodes API](https://www.elastic.co/docs/api/doc/elasticsearch/operation/operation-cat-nodes) to get the current `heap.percent` for each node.
```json
```

To get the JVM memory usage for each circuit breaker, use the [node stats API](https://www.elastic.co/docs/api/doc/elasticsearch/operation/operation-nodes-stats).
```json
```


## Prevent circuit breaker errors

**Reduce JVM memory pressure**
High JVM memory pressure often causes circuit breaker errors. See [High JVM memory pressure](https://docs-v3-preview.elastic.dev/elastic/docs-content/pull/4236/troubleshoot/elasticsearch/high-jvm-memory-pressure).
**Avoid using fielddata on `text` fields**
For high-cardinality `text` fields, fielddata can use a large amount of JVM memory. To avoid this, Elasticsearch disables fielddata on `text` fields by default. If you’ve enabled fielddata and triggered the [fielddata circuit breaker](https://docs-v3-preview.elastic.dev/elastic/elasticsearch/tree/main/reference/elasticsearch/configuration-reference/circuit-breaker-settings#fielddata-circuit-breaker), consider disabling it and using a `keyword` field instead. See [`fielddata` mapping parameter](https://docs-v3-preview.elastic.dev/elastic/elasticsearch/tree/main/reference/elasticsearch/mapping-reference/text#fielddata-mapping-param).
**Clear the fielddata cache**
If you’ve triggered the fielddata circuit breaker and can’t disable fielddata, use the [clear cache API](https://www.elastic.co/docs/api/doc/elasticsearch/operation/operation-indices-clear-cache) to clear the fielddata cache. This may disrupt any in-flight searches that use fielddata.
```json
```