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facebook / create-react-app

Set up a modern web app by running one command.
https://create-react-app.dev
MIT License
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Cannot read property 'forEach' of undefined #10242

Open KovbenyaAlexander opened 3 years ago

KovbenyaAlexander commented 3 years ago

Hello I created a project using npx create-react-app my-app. If i use npm start, compilation is successful, but the page is blank. I have not made any changes to the project. The console contains an 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

Screenshot: 2020-12-12 (2)

yves-zhou commented 3 years ago

Today, I found this problem.

avihaymenahem commented 3 years ago

Same here, running from npx here causes the same issue (no modifications maded)

EDIT: A workaround for now so you can keep on working: Disable the React DEV TOOLS extension on Chrome.

The problem comes from the global Hook which initiated wrong (Missing renderers prop on the object, which needs to be initiated with new Map())

KovbenyaAlexander commented 3 years ago

@avihaymenahem lol, I installed this extension and now the project is working correctly. but only in a browser with the extension

blockmood commented 3 years ago

@KovbenyaAlexander Close the Browser react plugin。

albiummid commented 3 years ago

@avihaymenahem lol, I installed this extension and now the project is working correctly. but only in a browser with the extension

that also worked for me. XD

arron-chen commented 3 years ago

so did i,how to do?

arron-chen commented 3 years ago

disabled the browser devtools will be fine, but i need this devtools to debug?

hechengxixi commented 3 years ago

@arron-chen the same case with me. do you find better way to debug?

KevinAdu commented 2 years ago

Did this issue ever get solved?

callisto1337 commented 2 years ago

the same case

voidoperator commented 1 year ago

i've been getting a similar error when clearing localStorage manually (which is set by a useEffect, the data stored is an object that i'm state managing with react's context API).

Uncaught TypeError: Cannot read properties of undefined (reading 'forEach')
    at setup (backendManager.js:656:17)
    at welcome (backendManager.js:640:3)
jarrodmjack commented 1 year ago

@voidoperator I am getting this exact same issue with localstorage but cannot find a fix

Shaker-Hamdi commented 1 year ago

I'm not even using "Create React App" and I'm getting the same issue with "Vite" and "Next.js". I think it's a "React Dev Tool" issue.

idilTugba commented 12 months ago
thany commented 3 months ago

I'm getting this error without the react devtools as well. All I have to do is access my website running om localhost, through BrowserStack. Not sure what is happening, but it should be easy to reproduce with any CRA.