Cancel an ongoing reindex task

POST /_reindex/{task_id}/_cancel

Auth

If wait_for_completion is true (the default), the response contains the final task state after cancellation. If wait_for_completion is false, the response contains only acknowledged: true.

This API follows reindex tasks across node-shutdown relocations, so callers can keep using the original task ID throughout the lifetime of the operation. Returned task IDs and timings reflect the original task, not its relocated successor. Relocated task IDs are also supported. They are followed transparently and return the task ID and timings of the original task.

When the task ID cannot be cancelled (unknown ID, non-reindex task, sliced child, finished task, or node left with no stored result), the API returns the following response with a 404 status code:

		{
  "error": {
    "type": "resource_not_found_exception",
    "reason": "reindex task [r1A2WoRbTwKZ516z6NEs5A:36619] either not found or completed"
  },
  "status": 404
}
		
	

During a brief handoff window of a node-shutdown relocation, you may receive the response below with a 503 status code. Retry with the same task ID; the retry follows the relocated task transparently.

		{
  "error": {
    "type": "status_exception",
    "reason": "cannot cancel task [36619] because it is being relocated"
  },
  "status": 503
}
		
	

Path parameters

task_id string required: The ID of the reindex task to cancel.

Query parameters

wait_for_completion boolean · default: true: If true (the default), the request blocks until the cancellation is complete and returns the final task state. If false, the request returns immediately with acknowledged: true.

Response

application/json

acknowledged boolean: Present and true when wait_for_completion=false.
completed boolean: Whether the reindex task has completed. Present when wait_for_completion=true.
id string: The ID of the reindex task. The value is the ID assigned when the task was first created and remains stable across node-shutdown relocations. Present when wait_for_completion=true.
description string: A sanitized description of the reindex operation.
start_time_in_millis number: The time at which the reindex task started, in milliseconds since the Unix epoch.
start_time string: The time at which the reindex task started, as an ISO 8601 formatted string.
running_time string: The elapsed running time of the reindex task, in a human-readable format. Only present when the request includes the ?human=true query parameter.
running_time_in_nanos number: The elapsed running time of the reindex task, in nanoseconds.
cancelled boolean: Whether the reindex task has been cancelled.
status object: The status of the reindex operation at the time of cancellation.
error object: The error that caused the reindex task to fail, if any.
response object: The final result of the reindex operation, if it completed before being cancelled.