# Issue with Config File

**URL:** <https://pdfjs.community/t/issue-with-config-file/1031>\
**Category:** Technical Support\
**Tags:** pdfjs-express\
**Created:** [October 6, 2021, 7:53am UTC](https://pdfjs.community/t/issue-with-config-file/1031 "2021-10-06T07:53:54Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![drevel](https://avatars.discourse-cdn.com/v4/letter/d/ee59a6/32.png) [@drevel](https://pdfjs.community/u/drevel)\
**Post date:** [October 6, 2021, 7:53am UTC](https://pdfjs.community/t/issue-with-config-file/1031/1 "2021-10-06T07:53:55Z")

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Dear Support,  
I’m trying to train myself onto Config files by following your examples online.  
But I get an issue because with the message “instance is not defined”.  
One information is that I’m working on a Blazor project based onto your demo projet.

 ![image](https://canada1.discourse-cdn.com/flex031/uploads/pdfjscommunity/original/1X/faa45ee029b6e3811d22daa75bc3e72353691bee.png)

Do you know what i’m doing wrong ?  
Best Regards,

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<div class="post-metadata">

**Author:** ![system](https://canada1.discourse-cdn.com/flex031/uploads/pdfjscommunity/original/1X/ffbcd25c7d423db8d5acd5db201c272f4db306dd.png) [@system](https://pdfjs.community/u/system)\
**Post date:** [October 6, 2021, 7:53am UTC](https://pdfjs.community/t/issue-with-config-file/1031/2 "2021-10-06T07:53:59Z")

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**Hello, I’m Ron, an automated tech support bot 🤖**

While you wait for one of our customer support representatives to get back to you, please check out some of these documentation pages:

Guides:
- [Blazor project PDF.js Express WebViewer integration issues - MIME type issues](https://pdfjs.express/documentation/get-started/blazor/blazor-integration-issues#mime-type-issues)
- [Integrating PDF.js Express Viewer into an existing Blazor project - Integrate PDF.js Express Viewer](https://pdfjs.express/documentation/get-started-viewer/blazor/exist-project#integrate-pdf.js-express-viewer)
- [Integrating PDF.js Express Plus into an existing Blazor project - Integrate PDF.js Express WebViewer](https://pdfjs.express/documentation/get-started/blazor/exist-project#integrate-pdf.js-express-webviewer)

APIs:
- [UI.Header - get(dataElement)](https://pdfjs.express/api/UI.Header.html#get__anchor)
- [Core.Annotations.WidgetFlags - new WidgetFlags(options)](https://pdfjs.express/api/Core.Annotations.WidgetFlags.html#WidgetFlags__anchor)
- [Core.Math.Matrix - get(row, column)](https://pdfjs.express/api/Core.Math.Matrix.html#get__anchor)

Forums:
- [How to raise AnnotationsLoaded Event?](https://pdfjs.community/t/how-to-raise-annotationsloaded-event/1015/1)
- [Blazor Demo Error](https://pdfjs.community/t/blazor-demo-error/342/1)
- [IE 11 Not work on builded React code](https://pdfjs.community/t/ie-11-not-work-on-builded-react-code/227/1)

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<div class="post-metadata">

**Author:** ![Logan](https://yyz1.discourse-cdn.com/flex031/user_avatar/pdfjs.community/logan/32/13_2.png) [@Logan](https://pdfjs.community/u/Logan)\
**Post date:** [October 6, 2021, 8:32pm UTC](https://pdfjs.community/t/issue-with-config-file/1031/4 "2021-10-06T20:32:34Z")

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Hey!

In the future when creating topics, please fill out the issue template correctly.

`instance` is only available globally in version 8.0+. Are you using v8.0+? (This is why filling out the issue template correctly is useful 😉 )

Logan