Failed to parse failures array At least one of reason cause must be present – How to solve this Elasticsearch exception

Opster Team

August-23, Version: 6.8-8.9

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Briefly, this error occurs when Elasticsearch is unable to parse the failures array due to missing ‘reason’ or ’cause’ fields. This usually happens when there’s an issue with the data being indexed or the structure of the index itself. To resolve this, ensure that the data being indexed is in the correct format and that the index structure is properly defined. Also, check the Elasticsearch logs for more detailed error information. If the issue persists, consider reindexing the data or recreating the index.

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This guide will help you check for common problems that cause the log ” failed to parse failures array. At least one of {reason;cause} must be present ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: index, reindex.

Log Context

Log “failed to parse failures array. At least one of {reason;cause} must be present” class name is We extracted the following from Elasticsearch source code for those seeking an in-depth context :

 return new SearchFailure(searchExc; index; shardId; nodeId);
 } else {
 return new SearchFailure(searchExc; index; shardId; nodeId; RestStatus.fromCode(status));
 } else {
 throw new ElasticsearchParseException("failed to parse failures array. At least one of {reason;cause} must be present");
 }  @Override
 public String toString() {


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