PaddlePaddle/PaddleOCR · error

Unsupported worker request type "${type}".

Error message

Unsupported worker request type "${type}".

What it means

The worker's message dispatcher (createPaddleOCRWorkerMessageHandler) only accepts the request types 'init', 'predict', and 'dispose'. Any other type string hits the default branch and throws; the error propagates back over the worker transport as a rejected response. This indicates a version mismatch between main-thread client and worker bundle, or direct misuse of the low-level transport.

Source

Thrown at paddleocr-js/packages/core/src/pipelines/ocr/worker-entry.ts:52

    return ocr.predict(sources, (payload.params || {}) as OcrRuntimeParamsInput);
  }

  async function handleDispose() {
    await ocr?.dispose();
    ocr = null;
    return {};
  }

  return async function handleMessage(type: string, payload: Record<string, unknown>) {
    switch (type) {
      case "init":
        return handleInit(payload);
      case "predict":
        return handlePredict(payload);
      case "dispose":
        return handleDispose();
      default:
        throw new Error(`Unsupported worker request type "${type}".`);
    }
  };
}

attachWorkerMessageHandler(createPaddleOCRWorkerMessageHandler());

View on GitHub (pinned to 2661c7c0ef)

Solutions

1. Ensure the worker bundle and main-thread library come from the same paddleocr-js version (rebuild, bust caches, verify lockfile dedupe).
2. Do not postMessage the OCR worker directly; go through the public API.
3. If you pass a custom createWorker, make sure it loads the matching worker-entry from the same package version.

Example fix

// before (custom code poking the worker)
worker.postMessage({ type: 'warmup' }); // unsupported

// after
worker.postMessage({ type: 'init', payload: { /* options */ } }); // or just use PaddleOCR.create()

try {
  await ocr.predict(image);
} catch (e) {
  if (e instanceof Error && e.message.includes('Unsupported worker request type')) {
    // worker bundle is from a different library version: hard-reload the page / rebuild
    location.reload(true);
    return;
  }
  throw e;
}

When it happens

Trigger: The worker bundle built from a different paddleocr-js version than the main-thread WorkerTransportClient (e.g. stale CDN cache or mixed versions in a monorepo); hand-rolled postMessage calls to the worker with an unknown type.

Common situations: Upgrading the library but the browser cached the old worker chunk; bundler misconfiguration producing worker-entry from a different package version; internal tooling posting custom messages to the OCR worker.

Related errors

• worker mode does not support a custom fetch implementation.
• worker must be a boolean or an options object.
• worker mode requires Web Worker support in this environment.
• PaddleOCR worker instance has been disposed.
• OCR worker is not initialized.

AI-assisted analysis of PaddlePaddle/PaddleOCR@2661c7c0ef (2026-08-14). Data as JSON: /api/errors/8e62f063bf449f16. Report an issue: GitHub.