Failed to cancel tasks on channel closed - Common causes and quick fixes

Failed to cancel tasks on channel closed – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 7.9-8.9

Briefly, this error occurs when Elasticsearch tries to cancel tasks but fails because the communication channel has already been closed. This could be due to network issues, node failures, or abrupt termination of tasks. To resolve this issue, you can try the following: 1) Check your network connectivity and ensure all nodes are properly connected. 2) Monitor your Elasticsearch cluster to identify any failing nodes and replace or fix them. 3) Ensure tasks are not being terminated abruptly, and if they are, investigate the cause.

This guide will help you check for common problems that cause the log ” failed to cancel tasks on channel closed ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: .

Log Context

Log “failed to cancel tasks on channel closed” classname is TaskManager.java.
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

        final Set tasks = channel.drainTasks();
        if (tasks.isEmpty() == false) {
            threadPool.generic().execute(new AbstractRunnable() {
                @Override
                public void onFailure(Exception e) {
                    logger.warn("failed to cancel tasks on channel closed"; e);
                }

                @Override
                protected void doRun() {
                    for (CancellableTask task : tasks) {