Windows 11 26H2 and Language Pack 24H2 and 25H2

Does anyone have a solution for installing language packs for version 26H2 when working with a .wim file? When I tried installing the packs via PowerShell, I was only able to add *.esd files, the Basic and OCR files (along with others) are not compatible with 26H2.

I ran a script to install the necessary packages, but I can’t even capture them after they’ve been downloaded I need to prepare a source image for the computers before adding it to WDS+MDT. I cannot afford to install these packages on several hundred machines all at once.

Does anyone have any ideas?

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To install language packs into a Windows version 26H2 install.wim image, you must use Deployment Image Servicing and Management (DISM). For a fully localized experience, you must inject the primary Language Pack (.cab), its corresponding Features on Demand (FOD) capabilities, and then seal it with the Latest Cumulative Update (LCU). [1, 2, 3]

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Phase 1: Prerequisites & Extraction

1. Download the Assets: Obtain the Windows 11 Language and Optional Features ISO matching your 26H2 architecture.
2. Isolate your files: Extract the contents of your target Windows ISO to a local directory (e.g., C:\ISO_Files).
3. Create Mount Folders: Create an empty workspace folder: [1, 2]
   
   cmd
   
   md C:\mount\windows
   Use code with caution.

Phase 2: Injecting the Language Pack & FODs

Open an elevated Deployment and Imaging Tools Environment (or Administrator Command Prompt) and run the following sequential blocks: [1]

1. Mount the .wim Image

Identify the target index number of your edition inside the WIM (e.g., Index 2 for Enterprise) and mount it: [1, 2, 3]

cmd

dism /Mount-Image /ImageFile:C:\ISO_Files\sources\install.wim /Index:2 /MountDir:C:\mount\windows
Use code with caution.

2. Install the Language Pack (.cab)

Add the core language pack package to the mounted image: [1, 2]

cmd

dism /Image:C:\mount\windows /Add-Package /PackagePath:"C:\Path_To_Language_ISO\Microsoft-Windows-Client-Language-Pack_x64_fr-fr.cab"
Use code with caution.

(Replace fr-fr with your target language identifier). [1]

3. Add Language Capabilities (FODs)

To prevent the OS from attempting to pull missing typing or text-to-speech items from Windows Update on boot, add the foundational capabilities: [1, 2]

cmd

dism /Image:C:\mount\windows /Add-Capability /CapabilityName:Language.Basic~~~fr-FR~0.0.1.0 /CapabilityName:Language.Handwriting~~~fr-FR~0.0.1.0 /CapabilityName:Language.OCR~~~fr-FR~0.0.1.0 /CapabilityName:Language.Speech~~~fr-FR~0.0.1.0 /CapabilityName:Language.TextToSpeech~~~fr-FR~0.0.1.0
Use code with caution.

4. Configure International Settings

Force the system's default UI experience to match the newly injected language package: [1]

cmd

dism /Image:C:\mount\windows /Set-AllIntl:fr-FR
Use code with caution.

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Phase 3: The Critical Update Rule

Crucial Step: When you inject language packs offline into modern Windows WIM images, you must re-apply the Latest Cumulative Update (LCU) at the end. If skipped, components can mismatch, causing localized settings apps to crash or fallback to English. [1, 2]

1. Download the newest 26H2 LCU .msu file from the Microsoft Update Catalog.
2. Inject it immediately after the language packs: [1]
   
   cmd
   
   dism /Image:C:\mount\windows /Add-Package /PackagePath:"C:\Updates\Windows11-KBxxxxxxx.msu"
   Use code with caution.

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Phase 4: Commit and Finalize

Save your changes and clean up the scratch directories to reduce file bloat: [1, 2]

cmd

dism /Unmount-Image /MountDir:C:\mount\windows /Commit
Use code with caution.

(Note: As verified by consensus among deployment engineers on NTLite Forums, you only need to perform these steps on the install.wim image. Modifying boot.wim is completely unnecessary unless you specifically want the early text of the Windows setup wizard screens to change languages). [1, 2]

24H2 thru 26H2 share the same Language Packs, and the same Language & Optional Features ISO.
Windows 11 24H2/25H2 Language and Optional Features ISO

If you want a ready-made script for integrating LP's and other files, abbodi1406's W10MUI is considered one of the better tools.
BatUtil/W10MUI at master · abbodi1406/BatUtil

Always integrate any LP's into a base image first, commit the changes to the image before applying the LCU again in a second pass.

A fully stable workflow for the latest versions of Windows 11 (from version 24H2, through 25H2, up to the current 26H2)
Here is the definitive summary of my golden rule for building images, which will protect you from errors in the future:

1. Mounting: Open a clean, unmodified .wim file.
2. LCU Update (First): Inject a gigabyte-sized cumulative update package (e.g., KB5127936) to bring the system kernel build to the latest version (e.g., .9818
3. Language Packs and Drivers (Next): Add language packs from the disk (Language and Optional Features ISO). The new kernel will automatically match them without reporting errors 14098 or 1726.
4. Modifications: Apply the registry settings (location sliders and Microsoft Update for Windows 11).
5. *Cleaning with /ResetBase*: Perform a deep, standard cleanup using only the /StartComponentCleanup command so that your WIM file is always as small as possible (it’s perfectly optimized). The component store will never become corrupted because /ResetBase is run only once during the lifetime of that specific file.
5.1 *Cleaning without /ResetBase: Every month, you mount the same file you created the previous month and simply add new LCUs to it without performing a deep cleanup.
• Advantages: You don’t have to install language packs every month (because they’re already there).
• Disadvantages: The WIM file grows by several hundred megabytes each month. Installation via MDT on new computers slows down over time.
6. Commit and close: You perform the installation with the /Commit parameter.

A brief summary of my work.

Monthly Clean Build with /ResetBase — THE BEST OPTION FOR MDT
Every month, you take a completely clean, original WIM file from the ISO (RTM version) and run your unified .bat script on it.
• How it works: Every month, the script installs the latest LCU from scratch, followed by languages and the registry, and finally performs a deep cleanup using the /ResetBase switch.
• Advantages: The WIM file is always the smallest possible size (it’s perfectly optimized). The component store will never become corrupted, because /ResetBase is run only once during the lifetime of that specific file.
• Conclusion: Since you already have a ready-made, fully automated .bat script that does everything in one go in just a few minutes, this method is the most optimal.