Updating max merged segment from mb to – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 2.3-2.3

Briefly, this error occurs when Elasticsearch is trying to update the maximum size of a merged segment, but the new size is not specified or is invalid. This could be due to a configuration error or a bug in the software. To resolve this issue, you can check your Elasticsearch configuration for any errors related to the ‘max_merged_segment’ setting. Ensure that the value is a valid size in megabytes. If the problem persists, consider updating or reinstalling Elasticsearch to fix any potential software bugs.

This guide will help you check for common problems that cause the log ” updating [max_merged_segment] from [{}mb] to [{}] ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: index, merge and shard.

Log Context

Log “updating [max_merged_segment] from [{}mb] to [{}]” classname is MergePolicyConfig.java.
We extracted the following from Elasticsearch source code for those seeking an in-depth context :


        final double oldMaxMergedSegmentMB = mergePolicy.getMaxMergedSegmentMB();
        final ByteSizeValue maxMergedSegment = settings.getAsBytesSize(INDEX_MERGE_POLICY_MAX_MERGED_SEGMENT; null);
        if (maxMergedSegment != null && maxMergedSegment.mbFrac() != oldMaxMergedSegmentMB) {
            logger.info("updating [max_merged_segment] from [{}mb] to [{}]"; oldMaxMergedSegmentMB; maxMergedSegment);

        final double oldReclaimDeletesWeight = mergePolicy.getReclaimDeletesWeight();
        final double reclaimDeletesWeight = settings.getAsDouble(INDEX_MERGE_POLICY_RECLAIM_DELETES_WEIGHT; oldReclaimDeletesWeight);


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?