What causes "cannot destroy running task" in hashicorp/nomad?

Call StopTask first and wait for the task to exit, then DestroyTask

cannot destroy running task

Error message

cannot destroy running task

What it means

DestroyTask in the QEMU driver refuses to destroy a task whose handle reports IsRunning() unless force=true. This is a safety guard preventing destruction of a live task without an explicit forced request.

Source

Thrown at drivers/qemu/driver.go:772

	// not be around when we call exec.shutdown
	if err := handle.exec.Shutdown(signal, timeout); err != nil {
		if handle.pluginClient.Exited() {
			return nil
		}
		return fmt.Errorf("executor Shutdown failed: %v", err)
	}

	return nil
}

func (d *Driver) DestroyTask(taskID string, force bool) error {
	handle, ok := d.tasks.Get(taskID)
	if !ok {
		return drivers.ErrTaskNotFound
	}

	if handle.IsRunning() && !force {
		return fmt.Errorf("cannot destroy running task")
	}

	if !handle.pluginClient.Exited() {
		if err := handle.exec.Shutdown("", 0); err != nil {
			handle.logger.Error("destroying executor failed", "error", err)
		}

		handle.pluginClient.Kill()
	}

	d.tasks.Delete(taskID)
	return nil
}

func (d *Driver) InspectTask(taskID string) (*drivers.TaskStatus, error) {
	handle, ok := d.tasks.Get(taskID)
	if !ok {
		return nil, drivers.ErrTaskNotFound

View on GitHub (pinned to 482b49bf1a)

Solutions

Call StopTask first and wait for the task to exit, then DestroyTask
Call DestroyTask with force=true to kill and destroy the running task
Verify the QEMU process state; if it hung, force-destroy and investigate why shutdown timed out

Example fix

// before
err := driver.DestroyTask(taskID, false) // cannot destroy running task
// after
if err := driver.StopTask(taskID, 30*time.Second, "SIGTERM"); err != nil {
    _ = driver.DestroyTask(taskID, true) // force
} else {
    _ = driver.DestroyTask(taskID, false)
}

Defensive patterns

Strategy: validation

Validate before calling

// Go: check running state before destroy
if h, ok := drv.tasks.Get(taskID); ok && h.IsRunning() {
    // must stop first or use force=true
}

Try / catch

if err := drv.DestroyTask(id, false); err != nil && strings.Contains(err.Error(), "cannot destroy running task") {
    err = drv.DestroyTask(id, true)
}

Prevention

Stop tasks before destroying them
Use force=true only when intentional
Track task lifecycle state in your tooling

When it happens

Trigger: Calling DestroyTask(taskID, false) while the QEMU task handle is still running. Only DestroyTask(taskID, true) bypasses the check.

Common situations: Task cleanup after a failed StopTask where the process never exited; scripts calling DestroyTask without stopping the task first; WaitResponse not yet received by the handle.

Related errors

AI-assisted analysis of hashicorp/nomad@482b49bf1a (2026-09-04). Data as JSON: /api/errors/3ed3321b83f27b6f. Report an issue: GitHub.