Unexpectedly failed to process queue item – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 8.3-8.9

Briefly, this error occurs when Elasticsearch is unable to process an item in the queue due to issues like high load, insufficient resources, or a bug in the system. To resolve this, you can try increasing the system resources, optimizing your queries to reduce load, or updating Elasticsearch to the latest version to fix potential bugs. Additionally, check your logs for more specific error messages that could indicate the root cause of the problem.

This guide will help you check for common problems that cause the log ” unexpectedly failed to process queue item ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: queue, cluster.

Log Context

Log “unexpectedly failed to process queue item” classname is JoinValidationService.java.
We extracted the following from Elasticsearch source code for those seeking an in-depth context :


        public void onFailure(Exception e) {
            logger.error("unexpectedly failed to process queue item"; e);
            assert false : e;

        public String toString() {


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