This error occurs when attempting to use the worker_threads module in a Node.js environment where worker threads are unavailable, either due to an outdated version, custom build configuration, or missing experimental flags in older versions.
This error indicates that the Node.js runtime you're using either doesn't support worker threads or has them explicitly disabled. Worker threads provide the ability to run JavaScript code in parallel threads, useful for CPU-intensive operations. The error appears when code attempts to import or use the worker_threads module, but the feature is unavailable in your current Node.js build. The most common cause is using an outdated Node.js version (pre-10.5.0) or attempting to use worker threads in Node.js versions 10.5.0-11.6.x without the required experimental flag. In rare cases, this error can occur with custom Node.js builds compiled without worker threads support or in environments like Electron that manage the V8 platform differently.
First, verify which Node.js version you're running:
node --versionWorker threads require Node.js 10.5.0 or later. If your version is older, you'll need to upgrade to use worker threads.
For the best experience, upgrade to Node.js 11.7.0+ where worker threads are stable and enabled by default:
# Using nvm (Node Version Manager)
nvm install 18
nvm use 18
# Or download from nodejs.org
# https://nodejs.org/Node.js 18 LTS or later is recommended for production use with worker threads.
If you're stuck on Node.js versions 10.5.0 through 11.6.x, you must use the experimental flag:
node --experimental-worker your-script.jsNote that this is only a temporary solution - these versions are no longer maintained and should be upgraded.
Ensure you're importing worker_threads correctly:
// CommonJS
const { Worker, isMainThread, parentPort, workerData } = require('worker_threads');
// ES Modules
import { Worker, isMainThread, parentPort, workerData } from 'worker_threads';In older Node.js versions, you may need to use the 'node:' prefix:
import { Worker } from 'node:worker_threads';If you're using a custom Node.js build or Electron, verify worker threads weren't disabled at compile time:
# Check if worker_threads is available
node -e "console.log(require('worker_threads'))"For Electron applications, ensure worker threads are properly configured in your build setup. You may need to add specific webpack configuration or use the threads package with proper bundler settings.
Custom Node.js builds: If Node.js was compiled with NODE_USE_V8_PLATFORM=false (common in Electron or embedded environments), worker threads may be unavailable even in supported versions. This requires modifying the Node.js build configuration or using a standard Node.js distribution.
Webpack bundling: When bundling applications that use worker_threads, ensure your webpack config has target: "node" and doesn't attempt to bundle the worker_threads module. Use webpack externals to exclude it from bundling.
Docker and containers: Some minimal Node.js container images may have worker threads disabled for size optimization. Use official Node.js images (node:18-alpine or similar) to ensure full feature availability.
Testing availability: You can check if worker threads are available programmatically:
try {
require.resolve('worker_threads');
console.log('Worker threads are available');
} catch (err) {
console.log('Worker threads are NOT available');
}Performance considerations: Worker threads are designed for CPU-intensive JavaScript operations. Don't use them for I/O-bound tasks - Node.js's asynchronous I/O already handles those efficiently on the event loop.
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