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Clarify VFS folder mapping and fix the VFS locations table #488

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Clarify VFS folder mapping and fix the VFS locations table #488

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35 changes: 19 additions & 16 deletions msix-src/desktop/desktop-to-uwp-behind-the-scenes.md
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@@ -1,7 +1,7 @@
---
title: Understanding how packaged desktop apps run on Windows
description: This topic provides a deep dive into how the OS behaves with packaged desktop apps.
ms.date: 09/09/2025
ms.date: 07/03/2026
ms.topic: concept-article
keywords: windows 11, windows 10, uwp, msix
ms.assetid: a399fae9-122c-46c4-a1dc-a1a241e5547a
Expand Down Expand Up @@ -94,21 +94,24 @@ This section applies only to virtualized apps.
This table shows where files shipping as part of your package are overlaid on the system for the app. Your app will perceive these files to be in the listed system locations when in fact they're in the redirected locations inside `C:\Program Files\WindowsApps\<package_full_name>\VFS`. The *FOLDERID* locations are from the [**KNOWNFOLDERID**](/windows/win32/shell/knownfolderid) constants.

| System location | Redirected location (Under \[<package_root>\]\VFS\) | Valid on architectures |
:--- | :--- | :---
*FOLDERID_SystemX86* | `SystemX86` | x86, amd64
*FOLDERID_System* | `SystemX64` | amd64
*FOLDERID_ProgramFilesX86* | `ProgramFilesX86` | x86, amd6
*FOLDERID_ProgramFilesX64* | `ProgramFilesX64` | amd64
*FOLDERID_ProgramFilesCommonX86* | `ProgramFilesCommonX86` | x86, amd64
*FOLDERID_ProgramFilesCommonX64* | `ProgramFilesCommonX64` | amd64
*FOLDERID_Windows* | `Windows` | x86, amd64
*FOLDERID_ProgramData* | Common `AppData` | x86, amd64
*FOLDERID_System*\catroot | `AppVSystem32Catroot` | x86, amd64
*FOLDERID_System*\catroot2 | `AppVSystem32Catroot2` | x86, amd64
*FOLDERID_System*\drivers\etc | `AppVSystem32DriversEtc` | x86, amd64
*FOLDERID_System*\driverstore | `AppVSystem32Driverstore` | x86, amd64
*FOLDERID_System*\logfiles | `AppVSystem32Logfiles` | x86, amd64
*FOLDERID_System*\spool | `AppVSystem32Spool` | x86, amd64
| :--- | :--- | :--- |
| *FOLDERID_SystemX86* | `SystemX86` | x86, amd64 |
| *FOLDERID_System* | `SystemX64` | amd64 |
| *FOLDERID_ProgramFilesX86* | `ProgramFilesX86` | x86, amd64 |
| *FOLDERID_ProgramFilesX64* | `ProgramFilesX64` | amd64 |
| *FOLDERID_ProgramFilesCommonX86* | `ProgramFilesCommonX86` | x86, amd64 |
| *FOLDERID_ProgramFilesCommonX64* | `ProgramFilesCommonX64` | amd64 |
| *FOLDERID_Windows* | `Windows` | x86, amd64 |
| *FOLDERID_ProgramData* | Common `AppData` | x86, amd64 |
| *FOLDERID_System*\catroot | `AppVSystem32Catroot` | x86, amd64 |
| *FOLDERID_System*\catroot2 | `AppVSystem32Catroot2` | x86, amd64 |
| *FOLDERID_System*\drivers\etc | `AppVSystem32DriversEtc` | x86, amd64 |
| *FOLDERID_System*\driverstore | `AppVSystem32Driverstore` | x86, amd64 |
| *FOLDERID_System*\logfiles | `AppVSystem32Logfiles` | x86, amd64 |
| *FOLDERID_System*\spool | `AppVSystem32Spool` | x86, amd64 |

@DrusTheAxe Howard Kapustein (DrusTheAxe) Aug 2, 2026

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No mention of arm64


> [!NOTE]
> The preceding table is the complete set of VFS folders that Windows maps natively, without the [Package Support Framework (PSF)](../psf/package-support-framework.md). If your app needs to redirect a folder that isn't in this list, you can use the PSF to extend redirection to additional locations. Those extra folders are defined by the author of the PSF configuration, so there's no exhaustive list of them.

## Registry

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