The code in your [Middleware](https://nextjs.org/docs/advanced-features/middleware) or your [Edge API Routes](https://nextjs.org/docs/api-routes/edge-api-routes) is using a feature from Node.js runtime.
When running Next.js locally with `next dev`, your application will show in the console, and in your browser, which file is importing and using an unsupported module. This module must be avoided: either by not importing it, or by replacing it with a polyfill.
For example, you might replace the Node.js `crypto` module with the [Web Crypto API](<[https://developer.mozilla.org/en-US/docs/Web/API/Web_Crypto_API](https://nextjs.org/docs/api-reference/edge-runtime#web-crypto-apis)>).