Could not initialize aggregators – How to solve this Elasticsearch exception

Opster Team

August-23, Version: 6.8-8.9

Before you dig into reading this guide, have you tried asking OpsGPT what this log means? You’ll receive a customized analysis of your log.

Try OpsGPT now for step-by-step guidance and tailored insights into your Elasticsearch operation.

Briefly, this error occurs when Elasticsearch fails to initialize the aggregators due to issues like insufficient memory, incorrect aggregation query, or a bug in the Elasticsearch version. To resolve this, you can increase the heap size to provide more memory, correct the aggregation query if it’s wrong, or upgrade Elasticsearch to the latest stable version to fix potential bugs. Also, ensure that the field you’re trying to aggregate on exists and is of the correct data type.

For a complete solution to your to your search operation, try for free AutoOps for Elasticsearch & OpenSearch . With AutoOps and Opster’s proactive support, you don’t have to worry about your search operation – we take charge of it. Get improved performance & stability with less hardware.

This guide will help you check for common problems that cause the log ” Could not initialize aggregators ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: search, aggregations.

Log Context

Log “Could not initialize aggregators” class name is We extracted the following from Elasticsearch source code for those seeking an in-depth context :

 try {
 bucketCollector = MultiBucketCollector.wrap(true; List.of(context.aggregations().aggregators()));
 } catch (IOException e) {
 throw new AggregationInitializationException("Could not initialize aggregators"; e);
 final Collector collector;
 if (context.aggregations().factories().context() != null
 && context.aggregations().factories().context().isInSortOrderExecutionRequired()) {
 TimeSeriesIndexSearcher searcher = new TimeSeriesIndexSearcher(context.searcher(); getCancellationChecks(context));


How helpful was this guide?

We are sorry that this post was not useful for you!

Let us improve this post!

Tell us how we can improve this post?