Iteration order of bucketOrds changed without mutating – How to solve this Elasticsearch exception

Opster Team

August-23, Version: 7.9-7.15

Briefly, this error occurs when the iteration order of bucketOrds in Elasticsearch changes without any mutation. This is usually due to a bug in the code or an unexpected change in the data structure. To resolve this issue, you can try to identify and fix the bug in the code that is causing the change in iteration order. Alternatively, you can check the data structure for any unexpected changes and correct them. If the error persists, consider upgrading your Elasticsearch version as it might be a known issue that has been fixed in a newer version.

This guide will help you check for common problems that cause the log ” Iteration order of [” + bucketOrds + “] changed without mutating. [ ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: aggregations, search.

Log Context

Log “Iteration order of [” + bucketOrds + “] changed without mutating. [” class name is We extracted the following from Elasticsearch source code for those seeking an in-depth context :

 for (int ordIdx = 0; ordIdx < owningBucketOrds.length; ordIdx++) {
 List buckets = new ArrayList<>(bucketsInOrd[ordIdx]);
 LongKeyedBucketOrds.BucketOrdsEnum ordsEnum = bucketOrds.ordsEnum(owningBucketOrds[ordIdx]);
 while( {
 if (bucketOrdsToCollect[b] != ordsEnum.ord()) {
 throw new AggregationExecutionException("Iteration order of [" + bucketOrds + "] changed without mutating. ["
 + ordsEnum.ord() + "] should have been [" + bucketOrdsToCollect[b] + "]");
 buckets.add(; bucketDocCount(ordsEnum.ord()); subAggregationResults[b++]));
 results[ordIdx] =[ordIdx]; buckets);


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