# Win: Extension pde unknown by Win - how to fix?
**URL:** https://discourse.processing.org/t/win-extension-pde-unknown-by-win-how-to-fix/47117
**Category:** Processing
**Created:** [September 10, 2025, 9:16pm UTC](https://discourse.processing.org/t/win-extension-pde-unknown-by-win-how-to-fix/47117 "2025-09-10T21:16:09Z")
**Posts on this page:** 7
**Page:** 1
### Author:  [@Chrisir](https://discourse.processing.org/u/Chrisir)
#### Post date: [September 10, 2025, 9:16pm UTC](https://discourse.processing.org/t/win-extension-pde-unknown-by-win-how-to-fix/47117/1 "2025-09-10T21:16:09Z")
Hello all,
I was able to start a Sketch by clicking on a pde-file;
recently, this doesn’t work.
What’s a simple Sketch to associate pde with processing exe?
Chrisir
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### Author:  [@sableraph](https://discourse.processing.org/u/sableraph)
#### Post date: [September 10, 2025, 9:55pm UTC](https://discourse.processing.org/t/win-extension-pde-unknown-by-win-how-to-fix/47117/2 "2025-09-10T21:55:10Z")
Are you by any chance using the portable version of Processing? If so, that’s likely why .pde files no longer open on double-click. The portable build is meant for situations where someone can’t install software and needs to run Processing from a USB drive. It doesn’t set up file associations, which is why we don’t recommend it.
The best fix is to install Processing using the regular installer, which will set all necessary system integrations (including file associations), and restore the behavior you were expecting.
PS: If you used the installer and the file associations still don’t work, let me know and we can investigate further.
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### Author:  [@Chrisir](https://discourse.processing.org/u/Chrisir)
#### Post date: [September 10, 2025, 10:01pm UTC](https://discourse.processing.org/t/win-extension-pde-unknown-by-win-how-to-fix/47117/3 "2025-09-10T22:01:11Z")
no, normal version with installer
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### Author:  [@sableraph](https://discourse.processing.org/u/sableraph)
#### Post date: [September 11, 2025, 8:16am UTC](https://discourse.processing.org/t/win-extension-pde-unknown-by-win-how-to-fix/47117/5 "2025-09-11T08:16:00Z")
Which version of Windows and Processing are you using?
As a quick fix, you should be able to right-click a .pde → Open with → Choose another app → pick processing.exe from your Program Files folder, and check “Always use this app to open .pde files”
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### Author:  [@Chrisir](https://discourse.processing.org/u/Chrisir)
#### Post date: [September 11, 2025, 1:37pm UTC](https://discourse.processing.org/t/win-extension-pde-unknown-by-win-how-to-fix/47117/6 "2025-09-11T13:37:14Z")
There’s a checkbox for this in the Preferences dialog of the IDE
but it does nothing.
> [@sableraph](#):
>
> → Open with
This works, so thank you!
(needs to be open with, open alone doesn’t do the trick)
Chrisir
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### Author:  [@sableraph](https://discourse.processing.org/u/sableraph)
#### Post date: [September 11, 2025, 2:49pm UTC](https://discourse.processing.org/t/win-extension-pde-unknown-by-win-how-to-fix/47117/8 "2025-09-11T14:49:46Z")
Thanks for the update. It would still be helpful to know which version of Windows and Processing you’re using so we have a point of reference in case this issue comes up for other people.
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### Author:  [@Chrisir](https://discourse.processing.org/u/Chrisir)
#### Post date: [September 11, 2025, 3:16pm UTC](https://discourse.processing.org/t/win-extension-pde-unknown-by-win-how-to-fix/47117/9 "2025-09-11T15:16:48Z")
Win 10 with Processing 4.4.7