How to Troubleshoot Common Elasticsearch Errors

Kacper Bąk
3 min readFeb 20, 2023
Photo by Benjamin Dada on Unsplash

Elasticsearch is a popular open-source search engine that provides real-time search and analytics capabilities. Although it is a robust platform, it can still encounter bugs that require troubleshooting. In this article, I will talk about common Elasticsearch errors such as the ‘mapper_parsing_exception’ and ‘cluster_block_exception’ and provide solutions for each. Additionally, I will discuss indexing and search errors and provide tips on how to deal with them. With this guide, you will have the knowledge to fix common Elasticsearch errors and improve your Elasticsearch skills.

“Mapper_parsing_exception” Error

The “mapper_parsing_exception” error is one of the most common errors in Elasticsearch. It occurs when the index mapping does not match the document structure. This error can be caused by several issues, including incorrect data types or conflicts between fields. To resolve this error, you need to start by reviewing the index mapping and comparing it to the document structure. You can also use the ‘explain’ API to get more information about the error and identify the problematic field.

“Cluster_block_exception” Error

The ‘cluster_block_exception’ error occurs when Elasticsearch blocks an index or shard due to a specific operation. This error can be caused by several reasons, including disk space issues, permission issues or read-only status. To fix this error, check the Elasticsearch logs and find the root cause of the problem. If the error is caused by disk space issues, you can free up some space or add more storage. If the error is caused by permission problems, you need to check user roles and permissions and make the necessary changes.

Indexing Errors

Indexing errors can occur when Elasticsearch fails to index a document. This error can be caused by several issues, including invalid data types, conflicts between fields, or lack of disk space. To resolve this error, start by reviewing the document and comparing it to the index mapping. You can also use the bulk API to index multiple documents at once and get more detailed error messages.

Search Errors

Search errors can occur when Elasticsearch fails to retrieve a document or returns an unexpected result. This error can be caused by several issues, including incorrect query syntax or search parameters. To resolve this error, start by reviewing the query and checking the query syntax. You can also use the ‘explain’ API to get more information about the search execution and identify the problematic query.

“Java OutOfMemory” Error

The ‘Java OutOfMemory’ error occurs when Elasticsearch runs out of memory and cannot allocate more memory. This error can be caused by several reasons, including insufficient heap space, a large number of shards, or heavy search queries. To fix this error, you need to increase the heap space by modifying the JVM settings. You can also reduce the number of shards or optimize search queries to avoid high memory consumption.

In summary, Elasticsearch errors can be a challenge to troubleshoot, but with the right knowledge and tools, they can be quickly identified and fixed. In this article, I have discussed some of the most common Elasticsearch errors and provided solutions for each error. By following my guide, you can improve your Elasticsearch skills and avoid common errors in the future.

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