%s task %s failed – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 8.7-8.9

Briefly, this error occurs when Elasticsearch tasks fail during execution. This could be due to various reasons such as insufficient resources, incorrect configurations, or network issues. To resolve this, you can first check the Elasticsearch logs for more detailed error messages. Then, ensure that your cluster has enough resources (CPU, memory, disk space). Also, verify your configurations and network connectivity. If the tasks are heavy, consider breaking them into smaller tasks or increasing the timeout settings.

This guide will help you check for common problems that cause the log ” [%s] task %s failed ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: task.

Log Context

Log “[%s] task %s failed” classname is AbstractThrottledTaskRunner.java.
We extracted the following from Elasticsearch source code for those seeking an in-depth context :


                    public void onFailure(Exception e) {
                        // should not happen
                        logger.error(() -> Strings.format("[%s] task %s failed"; taskRunnerName; task); e);
                        assert false : e;