# import WorkerFactory Error in React
**URL:** https://discourse.vtk.org/t/import-workerfactory-error-in-react/8936
**Category:** Web
**Created:** [July 12, 2022, 9:41am UTC](https://discourse.vtk.org/t/import-workerfactory-error-in-react/8936 "2022-07-12T09:41:39Z")
**Posts on this page:** 9
**Page:** 1
### Author:  [@lizemin2016](https://discourse.vtk.org/u/lizemin2016)
#### Post date: [July 12, 2022, 9:41am UTC](https://discourse.vtk.org/t/import-workerfactory-error-in-react/8936/1 "2022-07-12T09:41:39Z")
the import statement in `PiecewiseGaussianWidget.js` file bellow occurs error when compiled in react project.
```auto
import { W as WorkerFactory } from '../../_virtual/rollup-plugin-worker-loader__module_Sources/Interaction/Widgets/PiecewiseGaussianWidget/ComputeHistogram.worker.js';
```
who can tell me how to deal with the error.
Compiled with problems:X
ERROR in ./node\_modules/@kitware/vtk.js/Interaction/Widgets/PiecewiseGaussianWidget.js 546:23-36
export ‘W’ (imported as ‘WorkerFactory’) was not found in ‘…/…/\_virtual/rollup-plugin-worker-loader\_\_module\_Sources/Interaction/Widgets/PiecewiseGaussianWidget/ComputeHistogram.worker.js’ (possible exports: default)
---
### Author:  [@Forrest](https://discourse.vtk.org/u/Forrest)
#### Post date: [July 12, 2022, 1:39pm UTC](https://discourse.vtk.org/t/import-workerfactory-error-in-react/8936/2 "2022-07-12T13:39:19Z")
What version of vtk.js are you using? And is this with create-react-app?
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### Author:  [@lizemin2016](https://discourse.vtk.org/u/lizemin2016)
#### Post date: [July 12, 2022, 2:14pm UTC](https://discourse.vtk.org/t/import-workerfactory-error-in-react/8936/3 "2022-07-12T14:14:02Z")
vtkjs version:24.14.2, with create-react-app.
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### Author:  [@Forrest](https://discourse.vtk.org/u/Forrest)
#### Post date: [July 12, 2022, 2:26pm UTC](https://discourse.vtk.org/t/import-workerfactory-error-in-react/8936/4 "2022-07-12T14:26:12Z")
I would recommend upgrading if that is possible for you, since we are on v25 now. If upgrading is not possible, I can investigate to see if that version has a faulty export.
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### Author:  [@lizemin2016](https://discourse.vtk.org/u/lizemin2016)
#### Post date: [July 12, 2022, 3:35pm UTC](https://discourse.vtk.org/t/import-workerfactory-error-in-react/8936/5 "2022-07-12T15:35:56Z")
I have upgraded @kitware/vtk.js to the latest(v25.1.3), the error still exists…
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### Author:  [@Forrest](https://discourse.vtk.org/u/Forrest)
#### Post date: [July 12, 2022, 3:43pm UTC](https://discourse.vtk.org/t/import-workerfactory-error-in-react/8936/6 "2022-07-12T15:43:45Z")
Hm, it could be that create-react-app is auto-transforming `*.worker.js`, but I don’t imagine why they would be doing that for node\_modules. Do you have a minimal proof of concept repo that reproduces this problem?
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### Author:  [@lizemin2016](https://discourse.vtk.org/u/lizemin2016)
#### Post date: [July 12, 2022, 4:10pm UTC](https://discourse.vtk.org/t/import-workerfactory-error-in-react/8936/7 "2022-07-12T16:10:42Z")
[vtkjs-app.rar](https://discourse.vtk.org/uploads/short-url/zuNQElQrGCm8hNwADleASxOKif7.rar) (950.6 KB)
here is my simplified project, many thanks…
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### Author:  [@Forrest](https://discourse.vtk.org/u/Forrest)
#### Post date: [July 13, 2022, 6:30pm UTC](https://discourse.vtk.org/t/import-workerfactory-error-in-react/8936/8 "2022-07-13T18:30:06Z")
Ah, the rules you have in `config-overrides.js` is unnecessary. You don’t need the worker-loader, since that worker file is already transpiled in the `@kitware/vtk.js` package.
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### Author:  [@lizemin2016](https://discourse.vtk.org/u/lizemin2016)
#### Post date: [July 14, 2022, 2:49am UTC](https://discourse.vtk.org/t/import-workerfactory-error-in-react/8936/9 "2022-07-14T02:49:11Z")
Thank you, Forrest, my friend, I think too much…