Cannot read property 'forEach' of undefined (React)

Question

Today I started learning react! and I am having difficulties.

I created a project using npx create-react-app my-app. If I use npm start, the application does not work. I have not made any changes to the project

The console contains this error:

react-refresh-runtime.development.js:465 Uncaught TypeError: Cannot read property 'forEach' of undefined
    at Object.injectIntoGlobalHook (react-refresh-runtime.development.js:465)
    at Object../node_modules/@pmmmwh/react-refresh-webpack-plugin/client/ReactRefreshEntry.js (ReactRefreshEntry.js:8)
    at __webpack_require__ (bootstrap:856)
    at fn (bootstrap:150)
    at Object.1 (reportWebVitals.js:14)
    at __webpack_require__ (bootstrap:856)
    at checkDeferredModules (bootstrap:45)
    at Array.webpackJsonpCallback [as push] (bootstrap:32)
    at main.chunk.js:1

How i can fix this error?

Did you add any dependency while installing the application? Also, did you try creating a brand new react app to see if the error still persists? — Siddhant Varma
– Siddhant Varma, Commented Dec 12, 2020 at 16:32
Siddhant Varma, yes i tried to re-create the app. but it did not help — Kovbenya Alexander
– Kovbenya Alexander, Commented Dec 12, 2020 at 16:50
cssyphus, this is the deffault react-project - github.com/KovbenyaAlexander/react-app — Kovbenya Alexander
– Kovbenya Alexander, Commented Dec 12, 2020 at 17:09

designorant · Accepted Answer · 2021-02-04 10:38:08Z

7

It appears that this issue has been around for a couple of months now, catching those who are new to Create React App. It's rather unfortunate but depending on your CRA version the solution is to either:

Install React Dev Tools plugin
Update React Dev Tools plugin
Uninstall/Disable React Dev Tools plugin

I've documented it here: https://github.com/facebook/create-react-app/issues/10500

answered Feb 4, 2021 at 10:38

designorant

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2 Comments

RegarBoy Over a year ago

Thanks a lot man, I was thinking the issue was NextJS spicific, agh who could have thought new dev-tools I have installed last week could cause this without details?

Nevitones Over a year ago

It is affecting BrowserStack too but disabling the React plugin saved the day! Thanks!

elialvaradoo · Accepted Answer · 2020-12-12 17:11:47Z

0

when you ran create-react-app my-app, you created a new directory called my-app. you need to make sure you're inside the my-app directory then when you run npm start it will open a browser window with a url of localhost:3000

answered Dec 12, 2020 at 17:11

elialvaradoo

1

2 Comments

Kovbenya Alexander Over a year ago

the web application opens. but the page is blank and the console contains the error "Cannot read property 'forEach' of undefined"

elialvaradoo Over a year ago

you must of adjusted something with the code, I would just scrap those files and make a new directory. what i like doing is making the directory i want to work in before creating the react app then you go into that directory and do create-react-app .

edo-edo · Accepted Answer · 2020-12-12 17:33:50Z

0

This project work fine for me, delete node_modules and run npm i in my-app directory

answered Dec 12, 2020 at 17:33

edo-edo

1

2 Comments

Kovbenya Alexander Over a year ago

it didn't help. ill try to reinstal nodejs

edo-edo Over a year ago

My node version is v14.15.1

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