The initial batch of Windows tablets powered by ARM processors, such as the Surface RT, utilized 32-bit ARM chipsets. Nonetheless, Windows 11 necessitates a 64-bit ARM device from its inception, and Microsoft is now completely phasing out support for 32-bit ARM applications.
Microsoft is currently releasing Windows 11 Insider Preview Build 25905 to the Canary Channel for Windows Insiders. This update eliminates support for 32-bit ARM UWP applications, and a list of affected applications will be shown during the setup process. If there is an alternative version of the application on the Microsoft Store, it will be displayed as an app update before the Windows update is installed. To access this update, you may need to click the "Get Updates" button on the Store's Library page. After the installation of the Windows update, you will only have the option to uninstall the incompatible app and attempt to download it again from the Microsoft Store, where a compatible version will be provided if available.
The reason behind Microsoft's decision to implement this change is due to Qualcomm's modern chipsets, which currently power all existing ARM Windows 10 and 11 devices. These chipsets have limited support for 32-bit ARM software, and it is expected that future chips will no longer include any 32-bit cores.
The good news is that this is unlikely to impact many applications. Most, if not all, 32-bit ARM Windows applications also have x86 versions for mainstream PCs, which Windows 11 can emulate on ARM devices. Although emulated apps may run slightly slower, they should still function properly.
It is also important to note that Microsoft's announcement does not mention Win32 applications, such as early versions of Microsoft Office for ARM. It is unclear if these apps will cease to work and, if so, when that might occur. Many of these applications have been updated to 64-bit ARM or have x86 alternatives that can be emulated.
The removal of 32-bit ARM support is currently active only in the Canary testing channel. It will take several weeks or months before this change is implemented on all ARM Windows PCs. At the moment, there is no specific timeline available for the rollout.