reactjs / reactjs/react.dev

Uncaught TypeError: Cannot read property 'unstable_cancelCallback' of undefined

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Description

I am having an issue with an exception every time I load a react page and have chrome developer tools open. Would anyone have any suggestions?

I am injecting react and react-dom using webpack, and the versions used are

Uncaught TypeError: Cannot read property 'unstable_cancelCallback' of undefined at react-dom.production.min.js:192 at react-dom.production.min.js:12 at Object.<anonymous> (react-dom.production.min.js:12) at u (bootstrap bb4ee82…:1370) at o (bootstrap bb4ee82…:772) at Object.<anonymous> (vendor.min.js:99413) at u (bootstrap bb4ee82…:1370) at bootstrap bb4ee82…:1422 at bootstrap bb4ee82…:1422

"react": "^16.7.0",
"react-dom": "^16.7.0",
"react-hot-loader": "^4.3.11",

webpack:///./node_modules/react-dom/umd/react-dom.production.min.js

Ec=Z.__SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED.Scheduler,ag=Ec.unstable_cancelCallback,Nd=Ec.unstable_now,Bh=Ec.unstable_scheduleCallback,Fh=Ec.unstable_shouldYield,Qd=null,Rd=null,Dh="function"===typeof setTimeout?setTimeout:void 0,lg="function"===typeof clearTimeout?clearTimeout:void 0;new Set;var pd=[],Pa=-1,oa={},E={current:oa},O={current:!1},wa=oa,rd=null,sd=null,T=function(a,b,c,d){return new nh(a,b,c,d)}

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with the react-dom.production.min.js stack trace and the listed React, React DOM, and react-hot-loader versions, then inspect how webpack injects those packages. Reproduce the exception with Chrome Developer Tools open and determine whether the dependency combination causes the missing Scheduler method. Done means the page loads without this uncaught TypeError in that setup.

Written by the indexing model from the issue text.

Assessment

Tech stack
javascript, react, webpack
Domain
frontend, web-dev
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
20/100

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