This article outlines several typical errors encountered in Elasticsearch and provides their solutions.

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1. Disk Full Leads to Read-Only Index

When the disk becomes full, Elasticsearch may set indices to read-only. After expanding the disk, the following errer may persist:

blocked by: [FORBIDDEN/12/index read-only / allow delete (api)]

To resolve, set all indices to non-read-only:

curl -XPUT -H "Content-Type: application/json" http://127.0.0.1:9200/_all/_settings -d '{"index.blocks.read_only_allow_delete": null}'

Refer to the official documentation for more details.

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2. index.highlight.max_analyzed_offset Limit Ecxeeded

Increase the maximum analyzed offset for highlighting:

PUT my-index-2023.02.03/_settings
{
  "index" : {
    "highlight.max_analyzed_offset" : 6000000
  }
}

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3. Maximum Number of Shards Reached

Error:

{
  "error": {
    "root_cause": [{
      "type": "validation_exception",
      "reason": "Validation Failed: 1: this action would add [2] total shards, but this cluster currently has [1000]/[1000] maximum shards open;"
    }],
    "type": "validation_exception",
    "reason": "Validation Failed: 1: this action would add [2] total shards, but this cluster currently has [1000]/[1000] maximum shards open;"
  },
  "status": 400
}

Solutions: There are three ways to increase the maximum shards per node.

• Using Kibana Console

PUT /_cluster/settings
{
  "persistent": {
    "cluster": {
      "max_shards_per_node": 10000
    }
  }
}

• Using the Command Line

curl -XPUT http://localhost:9200/_cluster/settings -H 'Content-Type:application/json' -d '
{
  "persistent": {
    "cluster": {
      "max_shards_per_node": 10000
    }
  }
}'

• Modifying the Configuration File

# elasticsearch.yml
cluster.max_shards_per_node: 10000

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4. Request Entity Too Large (ContentTooLongException)

Error: org.apache.http.ContentTooLongException: entity content is too long [111214807] for the configured buffer limit [104857600]

Adjust the buffer limit when using the Java High Level REST Client:

RequestOptions customOptions = RequestOptions.DEFAULT.toBuilder()
    .setHttpAsyncResponseConsumerFactory(
        new HttpAsyncResponseConsumerFactory.HeapBufferedResponseConsumerFactory(500 * 1024 * 1024) // 500 MB
    )
    .build();

SearchRequest searchReq = new SearchRequest(indexName);
searchClient.search(searchReq, customOptions);

SearchScrollRequest scrollReq = new SearchScrollRequest(scrollId);
searchClient.scroll(scrollReq, customOptions);

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5. Immense Term in Field Exceeds Max Length

Error: Document contains at least one immense term in field="content" (whose UTF8 encoding is longer than the max length 32766)...

For keyword fields, the default maximum length ignored is 32766. Set ignore_above to skip longer terms:

PUT /articles/_mapping
{
  "properties": {
    "writer": {
      "type": "keyword",
      "ignore_above": 32766
    }
  }
}

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6. Circuit Breaking Exception: Data Too Large

Error:

{
  "error" : {
    "root_cause" : [{
      "type" : "circuit_breaking_exception",
      "reason" : "[parent] Data too large, data for [<http_request>] would be [1010545440/963.7mb], which is larger than the limit of [986061209/940.3mb]...",
      "bytes_wanted" : 1010545440,
      "bytes_limit" : 986061209
    }],
    "type" : "circuit_breaking_exception",
    "reason" : "[parent] Data too large, data for [<http_request>] would be [1010545440/963.7mb]...",
    "bytes_wanted" : 1010545440,
    "bytes_limit" : 986061209
  },
  "status" : 429
}

To fix, increase the heap size by editing config/jvm.options:

-Xms10g
-Xmx10g

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These are common issues with straightforward resolutions. Always ensure your cluster configurations align with your data and query requirements.