In a recent support bulletin, Microsoft has acknowledged a serious bug introduced with Windows 11 25H2 (also known as the 2025 Update) that disrupts the Media Creation Tool on ARM64 devices.

What’s Going Wrong?

  • On affected ARM64 systems, users attempting to launch the Media Creation Tool now see an error message such as:

    “We’re not sure what happened, but we’re unable to run this tool on your PC.”

  • This issue is tied to version 26100.6584 of the Media Creation Tool, which Microsoft released on September 29, 2025. The tool “doesn’t support creating media for use on ARM64 devices,” and the high-level fix is still pending.

  • Interestingly, devices using ARM64 chips could previously use the tool to produce bootable media for x64 systems. That capability appears broken now as well.

Microsoft describes this as a “known issue” and points out it is unlikely to affect most users, since creating Windows installation media from an ARM64 device is a less common scenario.

Why Did This Happen?

Because Windows 11 25H2 is delivered as an enablement package layered on the same codebase as 24H2, several legacy or edge-case functionalities inherited from prior versions are subject to regression.

The Media Creation Tool itself has long been documented as supporting only x64 architectures (for creating installation media). On Microsoft’s own download pages, it states:

“Note: Windows 11 media creation tool cannot be used to create installation media for Arm-based PCs; it can only create media for x64 processors.”

That said, the tool had been partially usable in hybrid or indirect scenarios before; the 25H2 update appears to have broken even those fallback paths.

What You Can Do (Workarounds)

Microsoft’s current workaround is blunt but functional: use a PC with an x64 (AMD64/Intel) processor to run the Media Creation Tool and generate the installation media.

For ARM-based users or in environments where an x64 PC isn’t available, options are limited:

  • Download a Windows 11 ARM64 ISO directly (from Microsoft’s ARM download page) and use third-party tools to build installation media, possibly injecting required drivers.

  • Wait for Microsoft to issue a patch or update to restore native Media Creation Tool support on ARM64.

Outlook & Impact

Because creating bootable media from ARM64 devices tends to be a niche use case (e.g. devs, IT professionals, advanced users), Microsoft considers the bug low-priority for general consumers.

Still, for those relying on ARM-based Windows machines—such as certain Surface devices or custom ARM PCs—this limits usability. It may also complicate recovery, clean installs, or reinstalling Windows purely from ARM hardware.

Microsoft is expected to restore full Media Creation Tool support in a future servicing update, though no timeline has been published.