Task is not found – How to solve this Elasticsearch error

Task is not found – How to solve this Elasticsearch error

Opster Team

July-20, Version: 1.7-8.0

Before you begin reading this guide, we recommend you try running the Elasticsearch Error Check-Up which can resolve issues that cause many errors.

This guide will help you check for common problems that cause the log ” task is not found ” to appear. It’s important to understand the issues related to the log, so to get started, read the general overview on common issues and tips related to the Elasticsearch concepts: admin, node, task and cluster.

Advanced users might want to skip right to the common problems section in each concept or try running the Check-Up which analyses ES to pinpoint the cause of many errors and provides suitable actionable recommendations how to resolve them (free tool that requires no installation).

Log Context

Log”task [{}] is not found”classname  is TransportCancelTasksAction.java We extracted the following from Elasticsearch source code for those seeking an in-depth context :

} else {
  if (taskManager.getTask(request.getTaskId().getId()) != null) {
  // The task exists; but doesn't support cancellation
  throw new IllegalArgumentException("task [" + request.getTaskId() + "] doesn't support cancellation");
  } else {
  throw new ResourceNotFoundException("task [{}] is not found"; request.getTaskId());
  } else {
  for (CancellableTask task : taskManager.getCancellableTasks().values()) {
  if (request.match(task)) {

Run the Check-Up to get customized recommendations like this:


Heavy merges detected in specific nodes



A large number of small shards can slow down searches and cause cluster instability. Some indices have shards that are too small…


Recommendations Based on your specific ES deployment you should…

Based on your specific ES deployment you should…


X-PUT curl -H [a customized recommendation]


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