Unexpected failure executing task timeout handler – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 8.8-8.9

Briefly, this error occurs when Elasticsearch is unable to execute a task within the specified timeout period. This could be due to heavy load, insufficient resources, or network issues. To resolve this, you can increase the timeout value, optimize your queries for better performance, or scale up your Elasticsearch cluster to handle more load. Additionally, check for any network issues that might be causing delays in task execution.

This guide will help you check for common problems that cause the log ” unexpected failure executing task timeout handler ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: task, cluster, handler.

Log Context

Log “unexpected failure executing task timeout handler” classname is MasterService.java.
We extracted the following from Elasticsearch source code for those seeking an in-depth context :


        public void onFailure(Exception e) {
            logger.error("unexpected failure executing task timeout handler"; e);
            assert false : e;



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