﻿---
title: Rejected requests
description: When Elasticsearch rejects a request, it stops the operation and returns an HTTP 429 response code for a TOO_MANY_REQUESTS error. The returned HTTP response...
url: https://www.elastic.co/elastic/docs-builder/docs/2967/troubleshoot/elasticsearch/rejected-requests
products:
  - Elasticsearch
applies_to:
  - Elastic Cloud Serverless: Generally available
  - Elastic Stack: Generally available
---

# Rejected requests
When Elasticsearch rejects a request, it stops the operation and returns an HTTP `429` response code for a `TOO_MANY_REQUESTS` error. The returned HTTP response body includes information on why the operation was rejected. You can retry HTTP `429` errors, but it's generally best to implement [exponential backoff](https://en.wikipedia.org/wiki/Exponential_backoff) to avoid exacerbating performance issues.

## Check rejected tasks

Rejected requests are frequently caused by depleted resources. The most common of these are described here.

### Review thread pools

To check the number of rejected tasks for each thread pool, use the [cat thread pool API](https://www.elastic.co/docs/api/doc/elasticsearch/operation/operation-cat-thread-pool):
```json
```

A high ratio of `rejected` to `completed` tasks, particularly in the `search` and `write` thread pools, indicates that Elasticsearch regularly rejects requests.
The following examples demonstrate typical `queue capacity` errors.
- The API response body returns an `es_rejected_execution_exception` error:
  ```json
  {
      "shard" : 0,
      "node" : "XXXX",
      "reason" : {
         "reason" : "rejected execution of org.elasticsearch.common.util.concurrent.TimedRunnable@26c03d4a on QueueResizingEsThreadPoolExecutor[name = XXXXX/search, queue capacity = 1000, min queue capacity = 1000, max queue capacity = 1000, frame size = 2000, targeted response rate = 1s, task execution EWMA = 968.1ms, adjustment amount = 50, org.elasticsearch.common.util.concurrent.QueueResizingEsThreadPoolExecutor@70be0765[Running, pool size = 25, active threads = 25, queued tasks = 1000, completed tasks = 616499351]]",
         "type" : "es_rejected_execution_exception"
      },
      "index" : "my-index-000001"
  }
  ```
- The error log returns an `EsRejectedExecutionException` error:
  ```
  Caused by: org.elasticsearch.common.util.concurrent.EsRejectedExecutionException: rejected execution of org.elasticsearch.common.util.concurrent.TimedRunnable@1a25fe82 on QueueResizingEsThreadPoolExecutor[name = XXXXX/search, queue capacity = 1000, min queue capacity = 1000, max queue capacity = 1000, frame size = 2000, targeted response rate = 1s, task execution EWMA = 10.7ms, adjustment amount = 50, org.elasticsearch.common.util.concurrent.QueueResizingEsThreadPoolExecutor@6312a0bb[Running, pool size = 25, active threads = 25, queued tasks = 1000, completed tasks = 616499351]]
  ```

To troubleshoot ongoing thread pool rejection errors, check [task queue backlog due to thread pool](/elastic/docs-builder/docs/2967/troubleshoot/elasticsearch/task-queue-backlog#diagnose-task-queue-thread-pool). Refer to the [Threadpool Rejections video](https://www.youtube.com/watch?v=auZJRXoAVpI) for a troubleshooting walkthrough.

## Inspect circuit breakers

To check the number of tripped [circuit breakers](https://docs-v3-preview.elastic.dev/elastic/docs-builder/docs/2967/reference/elasticsearch/configuration-reference/circuit-breaker-settings), use the [node stats API](https://www.elastic.co/docs/api/doc/elasticsearch/operation/operation-nodes-stats).
```json
```

These statistics are cumulative from node startup. For more information, see [circuit breaker errors](https://www.elastic.co/elastic/docs-builder/docs/2967/troubleshoot/elasticsearch/circuit-breaker-errors).
Refer to the [Circuit Breaker Error video](https://www.youtube.com/watch?v=k3wYlRVbMSw) for a troubleshooting walkthrough.

## Analyze indexing pressure

Elasticsearch reserves part of its JVM for indexing. An error can occur if heap usage exceeds the [`indexing_pressure.memory.limit` setting](https://docs-v3-preview.elastic.dev/elastic/docs-builder/docs/2967/reference/elasticsearch/index-settings/pressure#memory-limits). To check the number of [indexing pressure](https://docs-v3-preview.elastic.dev/elastic/docs-builder/docs/2967/reference/elasticsearch/index-settings/pressure) rejections, use the [node stats API](https://www.elastic.co/docs/api/doc/elasticsearch/operation/operation-nodes-stats).
```json
```

These statistics are cumulative from node startup.
The following examples demonstrate indexing pressure rejections.
- The API response body returns an `es_rejected_execution_exception` error:
  ```json
  {
    "error" : {
      "root_cause" : [
        {
          "type" : "es_rejected_execution_exception",
          "reason" : "rejected execution of primary operation [coordinating_and_primary_bytes=XXXXX, replica_bytes=XXXXX, all_bytes=XXXXX, coordinating_operation_bytes=XXXXX, max_coordinating_and_primary_bytes=XXXXX]"
        }
      ],
      "type" : "es_rejected_execution_exception",
      "reason" : "rejected execution of coordinating operation [coordinating_and_primary_bytes=XXXXX, replica_bytes=XXXXX, all_bytes=XXXXX, coordinating_operation_bytes=XXXXX, max_coordinating_and_primary_bytes=XXXXX]"
    },
    "status" : 429
  }
  ```
- The error log returns an `EsRejectedExecutionException` error:
  ```
  Caused by: org.elasticsearch.common.util.concurrent.EsRejectedExecutionException: rejected execution of primary operation [coordinating_and_primary_bytes=XXXXX, replica_bytes=XXXXX, all_bytes=XXXXX, coordinating_operation_bytes=XXXXX, max_coordinating_and_primary_bytes=XXXXX]
  ```

As part of the [Reading and writing documents](https://www.elastic.co/elastic/docs-builder/docs/2967/deploy-manage/distributed-architecture/reading-and-writing-documents) outlined models, the portion of the error `rejected execution of <category> operation` reports one of the following categories: `combined_coordinating_and_primary`, `coordinating`, `primary`, or `replica`.
These errors are often related to:
- The quantity of [backlogged tasks](https://www.elastic.co/elastic/docs-builder/docs/2967/troubleshoot/elasticsearch/task-queue-backlog).
- The value of [Bulk index](https://www.elastic.co/docs/api/doc/elasticsearch/operation/operation-bulk) is set to too large of a size.
- Large search response sizes.
- Use of the [`semantic_text`](https://docs-v3-preview.elastic.dev/elastic/docs-builder/docs/2967/reference/elasticsearch/mapping-reference/semantic-text) field type, which can cause rejections when indexing large batches of documents if the batch may otherwise incur an Out of Memory (OOM) error. <applies-to>Elastic Stack: Generally available since 9.1</applies-to><applies-to>Elastic Cloud Serverless: Generally available</applies-to>

Refer to the [Index Pressure Rejections video](https://www.youtube.com/watch?v=QuV8QqSfc0c) for a troubleshooting walkthrough.

## Prevent rejected requests

<admonition title="Simplify monitoring with AutoOps">
  AutoOps is a [monitoring](https://www.elastic.co/elastic/docs-builder/docs/2967/deploy-manage/monitor) tool that simplifies cluster management through performance recommendations, resource utilization visibility, and real-time issue detection with resolution paths. Learn more about [AutoOps](https://www.elastic.co/elastic/docs-builder/docs/2967/deploy-manage/monitor/autoops).
</admonition>


### Fix high CPU and memory usage

If Elasticsearch regularly rejects requests and other tasks, your cluster likely has high CPU usage or high JVM memory pressure. For tips, refer to [High CPU usage](https://www.elastic.co/elastic/docs-builder/docs/2967/troubleshoot/elasticsearch/high-cpu-usage) and [High JVM memory pressure](https://www.elastic.co/elastic/docs-builder/docs/2967/troubleshoot/elasticsearch/high-jvm-memory-pressure).

### Fix for `semantic_text` ingestion issues

<applies-to>
  - Elastic Cloud Serverless: Generally available
  - Elastic Stack: Generally available since 9.1
</applies-to>

When bulk indexing documents with the [`semantic_text`](https://docs-v3-preview.elastic.dev/elastic/docs-builder/docs/2967/reference/elasticsearch/mapping-reference/semantic-text) field type, you might encounter rejections due to high memory usage during inference processing. These rejections appear as an `InferenceException` in your cluster logs.
To resolve this issue:
1. Reduce the batch size of documents in your indexing requests.
2. If reducing batch size doesn't resolve the issue, then consider scaling up your machine resources.
3. <applies-to>Elastic Cloud Serverless: Unavailable</applies-to> A last resort option is to adjust the `indexing_pressure.memory.coordinating.limit` cluster setting. The default value is 10% of the heap. Increasing this limit allows more memory to be used for coordinating operations before rejections occur.

<warning>
  This adjustment should only be considered after exhausting other options, as setting this value too high may risk Out of Memory (OOM) errors in your cluster. A cluster restart is required for this change to take effect.
</warning>