Monitoring execution has been rejected – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 6.8-8.9

Briefly, this error occurs when Elasticsearch is overloaded with tasks and can’t accept more. This is often due to high indexing or search load, or insufficient resources like CPU or memory. To resolve this, you can optimize your queries or indexing process to reduce load, increase the resources of your Elasticsearch cluster, or adjust the thread pool settings to allow more concurrent tasks. Also, consider using bulk operations for indexing and ensure your data is evenly distributed across all nodes to prevent hotspots.

This guide will help you check for common problems that cause the log ” monitoring execution has been rejected ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: plugin.

Log Context

Log “monitoring execution has been rejected” classname is
We extracted the following from Elasticsearch source code for those seeking an in-depth context :


                public void onRejection(Exception e) {
                    logger.warn("monitoring execution has been rejected"; e);


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