Article illustration 1

Microsoft has acknowledged a significant compatibility issue affecting Windows 11 devices powered by Arm64 processors following the rollout of the Windows 11 25H2 update (codenamed 2025 Update). The Windows Media Creation Tool—a critical utility for creating bootable installation media—fails to launch on these systems, displaying the error message: "We're not sure what happened, but we're unable to run this tool on your PC.

According to a support document published September 29, 2025, the failure specifically impacts Media Creation Tool version 26100.6584. While Arm64 devices typically support creating installation media for x64 systems, Microsoft confirmed this cross-architecture functionality is "not working as expected" in the latest release.

"The media creation tool doesn't support creating media for use on Arm64 devices. However, Arm64 devices are normally able to create media for x64 devices—this functionality is not working as expected," Microsoft stated.

Workarounds and Impact Assessment

Microsoft suggests affected users temporarily switch to AMD64-based systems to create installation media, emphasizing that the tool functions normally on traditional x64 architecture. The company downplayed widespread disruption, noting that media creation tasks are "rarely used on Arm64 devices." Nevertheless, the failure presents hurdles for IT administrators managing Arm-based Surface devices or developers testing multi-architecture environments.

Broader Update Context

The tool failure emerges alongside Microsoft's broader Windows 11 25H2 rollout—a minor update delivered via enablement package (eKB) that activates previously deployed features including:
- Enhanced Copilot capabilities
- Modernized Windows Hello interface
- Copilot+ PC exclusives like Recall (preview)
- UI, accessibility, and system management improvements

Microsoft engineers are actively investigating the Media Creation Tool failure but haven't provided an estimated resolution timeline. For now, Arm64 users requiring installation media must rely on alternative hardware—a notable inconvenience in an ecosystem increasingly embracing Arm architecture.

Source: BleepingComputer