Discussion on: 5 Steps to debugging Next.js/Node.js from VSCode or Chrome DevTools

[Eunjae Lee]

I don't know the exact difference, but for those of you who get address already in use issue,

try

"dev": "node --inspect node_modules/.bin/next",

[Vincent]

Hi there, which command were you using previously when getting "address already in use"? The blog post and documentation warns about this so I thought it would be good. The error comes from the fact that NODE_OPTIONS is sent to all child node processes so when running NODE_OPTIONS=.. yarn dev you're asking yarn to start in debugger mode and also nextjs, on the same port, which causes this error.

Also, you should be able to safely remove node_modules/.bin/ because that's already the default when running npm scripts.

[Eunjae Lee]

Hey, embarrassingly, I do not remember which command I was using yesterday. (It was literally yesterday, though)

anyway you're saying

NODE_OPTIONS='--inspect' next
node --inspect node_modules/.bin/next

These two commands are equivalent?
I didn't know. Thank you!

[Vincent]

I do not know if both of those commands are equivalent, what I know is that:

{
  "scripts": {
    "dev": "next"
  }

and

{
  "scripts": {
    "dev": "./node_nodules/.bin/next"
  }

are equivalent, because of: docs.npmjs.com/misc/scripts#path

What I wanted to say is that:

running

NODE_OPTIONS='--inspect' yarn dev

will fail because this starts two processes in debugger mode: yarn and nextjs. This is why you get the error message about already running debugging server.

NODE_OPTIONS can only be passed right next to the next command inside package.json.