ArcGIS setup files only install the English version, and not the language pack when installing on Windows 11 25H2

Description

When installing a localized product on Windows 11 25H2, Setup.exe will run the core product setup after the Windows 11 25H2 update, but not run the language pack.

This issue affects the localized setups for the following products:

• ArcGIS Pro 3.4 and 3.5
• ArcGIS Server 11.4 and 11.5
• ArcGIS Drone2Map 2024.2 and 2025.1
• ArcGIS AllSource 1.3 and 1.4
• ArcGIS Reality Studio 2025.1

Note:
Windows 11 25H2 is the ONLY operating system affected by this issue.

Cause

The Setup.exe isn’t correctly identifying the latest OS as a supported operating system.

Solution or Workaround

Manually install the language pack once the core product installation has completed. The language pack setup can be found in the SetupFiles\Supplement folder.

After downloading and extracting the executable, the language pack files can be found in the user’s Documents folder.  The following is an example of the path to ArcGIS Pro German supplement:

C:\Users\<userprofile>\Documents\ArcGIS Pro 3.5\ArcGISPro_German\SetupFiles\Supplement\ProGermanLP.msi