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

Opster Team

Aug-23, Version: 1-2.9

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Briefly, this error occurs when OpenSearch 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, you can try the following: 1) Check your network connectivity and ensure stable communication between nodes. 2) Monitor your nodes’ health and restart any failed ones. 3) Ensure tasks are not being terminated abruptly. 4) Review your OpenSearch logs for any additional information about the error.

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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 OpenSearch concepts: .

Log Context

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

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

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


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