Unable to set queue concurrency, worker not found

Error message

Unable to set queue concurrency, worker not found: '${queueName}'

What it means

setConcurrency looks up the BullMQ Worker instance for the given queue and sets its concurrency. If no worker object exists for that queue name, it logs this warning and returns without changing anything. Concurrency for that queue remains at its default.

Solutions

Call setConcurrency only after workers are initialized (after startWorkers resolves)
Run it in the process that actually consumes the queue (the microservices worker, not the API server)
Verify the QueueName value matches an existing registered queue exactly
Log/persist desired concurrency config and apply it in worker bootstrap if ordering is the issue

Example fix

// before
await app.listen(port);
jobRepository.setConcurrency(QueueName.MachineLearning, 2);
// after
await app.listen(port);
await jobRepository.startWorkers();
jobRepository.setConcurrency(QueueName.MachineLearning, 2);

Defensive patterns

Strategy: validation

Validate before calling

function canSetConcurrency(job: JobRepository, q: QueueName): boolean {
  return q in (job as any).workers;
}
if (!canSetConcurrency(job, QueueName.MachineLearning)) {
  await job.startWorkers(); // initialize workers first
}
job.setConcurrency(QueueName.MachineLearning, 2);

Type guard

function workerExists(job: JobRepository, q: QueueName): boolean {
  const workers = (job as unknown as { workers: Record<string, unknown> }).workers;
  return Boolean(workers?.[q]);
}

Prevention

Call setConcurrency only after startWorkers() completes
Only tune concurrency in the process consuming the queue (microservices)
Keep queue names in one enum to avoid typos
Apply concurrency settings during worker bootstrap, not at request time

When it happens

Trigger: setConcurrency(queueName, concurrency) is called for a QueueName whose worker hasn't been created yet in this.workers — e.g. called before worker initialization or for a queue that this process does not consume.

Common situations: Calling setConcurrency during startup before startWorkers registers workers; calling it on the API server process where workers run in microservices; a queue name typo or a queue removed in a newer version.

Understand the failure class

Background: 'Could not be found', 'does not exist', 'not found in database': the resource-not-found family when an ID, slug, key, or URI lookup comes back empty — this error's family across 20 libraries.

Related errors

AI-assisted analysis of immich-app/immich@e55ac299a4 (2026-09-15). Data as JSON: /api/errors/c45ac9fa9fb916f7. Report an issue: GitHub.

Appendix: source

Thrown at server/src/repositories/job.repository.ts:150

      }
    }
    this.microservicesPresent = isPresent;
  }

  async run({ name, data }: JobItem) {
    const item = this.handlers[name as JobName];
    if (!item) {
      this.logger.warn(`Skipping unknown job: "${name}"`);
      return JobStatus.Skipped;
    }

    return item.handler(data);
  }

  setConcurrency(queueName: QueueName, concurrency: number) {
    const worker = this.workers[queueName];
    if (!worker) {
      this.logger.warn(`Unable to set queue concurrency, worker not found: '${queueName}'`);
      return;
    }

    worker.concurrency = concurrency;
  }

  async isActive(name: QueueName): Promise<boolean> {
    const queue = this.getQueue(name);
    const count = await queue.getActiveCount();
    return count > 0;
  }

  async isPaused(name: QueueName): Promise<boolean> {
    return this.getQueue(name).isPaused();
  }

  pause(name: QueueName) {
    return this.getQueue(name).pause();

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