While doing some sanitization on a variable in Next.js I ran into this weird problem:

Module not found: Error: Can't resolve 'net'

You might have some variation of it, which says a core Node.js module is missing.

Do NOT npm install net or anything like that. If you already tried, run npm uninstall on those modules.

The problem is this: Next.js is trying to run backend code in the frontend.

In my case it was the DOMPurify library. I was using it inside the component, but instead I had to use it in the getStaticProps() method.

That method runs at build time in the Node environment, where that library expected to be ran into.

Lessons in this unit:

0:	Introduction
1:	Blank page after router.push() in Next.js?
2:	How to fix the error `PrismaClient is unable to be run in the browser` in Next.js
3:	Next.js, blank page after calling `res.redirect()`
4:	Next.js, how to fix the error `Constructor requires 'new' operator`
5:	▶︎ Next.js, fix the `module not found` error
6:	How to fix the `can't resolve module` error in Next.js
7:	How to fix error serializing Date object JSON in Next.js
8:	How to fix the `unable to resolve dependency tree` PostCSS and Tailwind issue in Next.js
9:	Fix “Module not found: Can't resolve encoding” in Next.js
10:	How to fix Your custom PostCSS configuration must export a `plugins` key.
11:	Next.js, what to do when the state of a component is not refreshed when navigating
12:	Revalidation and ISR gotcha on Vercel
13:	How to fix the `Already 10 Prisma Clients are actively running` error