mastra-ai/mastra · error · Error

Cannot restart task in status '${task.status}' (expected 'ru

Error message

Cannot restart task in status '${task.status}' (expected 'running')

What it means

restart() is only valid for tasks currently in the 'running' state; the manager throws this error for any other stored status. Restart semantics mean 'kill and re-run a running task', not 're-run an old finished task'.

Source

Thrown at packages/core/src/background-tasks/manager.ts:480

   *
   */
  async restart(taskId: string, context?: TaskContext): Promise<BackgroundTask> {
    if (this.shuttingDown) {
      throw new Error('BackgroundTaskManager is shutting down, cannot restart tasks');
    }
    if (!this.#mastra) {
      throw new Error('Mastra is not registered with this manager');
    }

    if (this.initPromise) await this.initPromise;

    const storage = await this.getStorage();
    const task = await storage.getTask(taskId);
    if (!task) {
      throw new Error(`Task not found: ${taskId}`);
    }
    if (task.status !== 'running') {
      throw new Error(`Cannot restart task in status '${task.status}' (expected 'running')`);
    }

    if (context) {
      this.registerTaskContext(task.id, context);
    }

    const canRun = await this.checkConcurrency(task.agentId);
    if (!canRun) {
      // Restart sits outside the queue/fallback-sync paths — there's no
      // synchronous caller to fall back to, and silently leaving the task
      // running hides the failure from the caller. Throw and let the
      // caller retry once a slot frees.
      throw new Error(`Concurrency limit reached, cannot restart task "${taskId}" — retry once a slot is available`);
    }

    await this.dispatch(task, true);

    return task;

View on GitHub (pinned to 75dd419e61)

Solutions

1. Check task.status === 'running' before calling restart; use resume() for suspended tasks.
2. For failed/completed tasks, start a new task with the same parameters instead of restart().
3. Refresh task state immediately before restart to avoid acting on stale status in UIs.

Example fix

// before
await manager.restart(taskId); // task already 'failed'
// after
const task = await manager.getTask(taskId);
if (task.status === 'running') await manager.restart(taskId);
else await manager.start(task.input); // fresh run for non-running tasks

async function assertRunning(manager, taskId) {
  const task = await manager.getTask(taskId);
  if (task?.status !== 'running') throw new Error(`Refusing restart: task status is ${task?.status}`);
}

function isRunningTask(task) {
  return !!task && task.status === 'running';
}

try {
  await manager.restart(taskId);
} catch (e) {
  const m = /Cannot restart task in status '(.+)'/.exec(e.message);
  if (m) {
    // route by actual status: suspended -> resume, else start new
  } else throw e;
}

When it happens

Trigger: Calling manager.restart(taskId) when the task's stored status is 'completed', 'failed', 'suspended', or 'cancelled' rather than 'running'.

Common situations: Restarting a task after it already finished (race between a status refresh and the restart call); attempting to retry a failed task with restart(); operator dashboards offering 'Restart' on finished tasks.

Related errors

• Cannot resume task in status '${task.status}' (expected 'sus
• tool_result must be preceded by a tool_call with the same to
• Unsupported Factory stage: ${stage}
• Mode "${mode.id}" transitionsTo cannot reference itself
• Mode "${mode.id}" transitionsTo references unknown mode "${m

AI-assisted analysis of mastra-ai/mastra@75dd419e61 (2026-08-30). Data as JSON: /api/errors/08bdfd55bbfdcda0. Report an issue: GitHub.