Microsoft fixes Media Creation Tool regression on Arm64 with KB5067036 (Windows 11 25H2)

Microsoft has quietly corrected a frustrating compatibility regression that left some Windows users — particularly owners of Arm64 devices and those running Windows 10 22H2 — unable to run the official Media Creation Tool (MCT) after the Windows 11 25H2 rollout, delivering the fix as part of the optional preview update KB5067036 while bundling it with a set of staged UI and Copilot-related feature previews.

Background / Overview​

The Media Creation Tool is Microsoft’s convenience utility for downloading Windows images and creating bootable USB installers. In late September 2025 Microsoft (and community reports) flagged a regression in the updated MCT binary identified by build metadata as 26100.6584: on some hosts the tool would start, show a brief Windows splash, ask for UAC elevation and then exit silently or present the generic message, “We’re not sure what happened, but we’re unable to run this tool on your PC.” This behavior was particularly visible when users attempted to run the MCT on Arm64 hosts or on some Windows 10 systems. Microsoft documented the symptom on its Release Health / Update History pages and advised workarounds while engineers investigated.
Why this mattered: the regression landed at a sensitive moment — just as administrators, enthusiasts and device owners were preparing update media and recovery sticks around end-of-support activity for older Windows versions. For imaging teams, OEM technicians, developers testing on Arm hardware, and users who expected to create recovery media on their Arm-based tablets and laptops, the broken MCT temporarily removed a trusted, single-file workflow and forced fallback to manual ISO downloads or third‑party USB tools.

What broke — technical symptoms and scope​

The symptom in practical terms​

• Launch the MCT (version 26100.6584), approve UAC, see a Windows splash for a second, then nothing — the tool quits with no useful diagnostic. Users sometimes instead saw the generic dialog text noted above.
• The failure was reproducible when attempting to create Arm64 media from an Arm64 host; Microsoft’s notes clarified that creating Arm64-targeted media from Arm hosts was not a supported workflow in the affected MCT binary, but the regression caused additional, visible breakage.

Who was affected​

• Primary surface: Arm64 hosts attempting to create Arm64 media. That pathway is niche but important for device builders and single-device owners.
• Secondary reports: some Windows 10 (22H2) hosts also reproduced an early-exit behavior with the updated MCT binary. Microsoft’s public advisories treated the problem as a compatibility regression rather than a security vulnerability.

Official guidance and short‑term workarounds​

Microsoft’s published guidance emphasized two safe and reliable alternatives while the issue was investigated:

• Use an x64 (Intel/AMD) host to create Arm64 installation media with the Media Creation Tool.
• Download the official Arm64 ISO from Microsoft’s Software Download page and write it to USB using a trusted third‑party tool such as Rufus or Ventoy, or use File Explorer / Diskpart workflows on a functioning host.

These workarounds are proven and safe: they deliver canonical, hashed ISO artifacts and avoid relying on the single-file convenience path that had regressed.

---

Timeline — discovery, acknowledgement, and remediation​

1. Late September 2025 — Microsoft shipped a Media Creation Tool binary referenced by community reporting as build 26100.6584. Soon after, multiple community reproductions reported silent exits on certain hosts.
2. Early October 2025 — Microsoft documented the behavior on its Update History / Release Health pages, called out the MCT build number and advised the official workarounds. The company classified the symptom as a known issue pending a fix.
3. October 28, 2025 — Microsoft issued the optional preview cumulative update KB5067036 (Release Preview / Week‑D preview) for Windows 11 versions 24H2 and 25H2, which included a remediation for the MCT failure and refreshed binaries for affected components. The KB also surfaced a host of user‑facing feature previews that are being rolled out gradually.
4. November 2025 Patch Tuesday — Microsoft planned to fold the KB5067036 fixes and feature previews into the regular cumulative update cadence (the scheduled Patch Tuesday distribution on November 11, 2025), at which point the fix would reach the mainstream update pipeline for most users. Note: preview updates are optional and staged; Patch Tuesday packaging typically makes the changes broadly available.

---

What KB5067036 changed — the MCT fix and bundled features​

KB5067036 is not a single-purpose hotfix; it is an optional, non‑security preview cumulative packaged as the lead for November’s servicing stream. It mixes a targeted compatibility correction with several visible UX and on‑device Copilot improvements.

The MCT remediation (what Microsoft fixed)​

• The KB’s release notes and Update History entries explicitly list the Media Creation Tool regression (the MCT binary version 26100.6584 failing to run on Arm64 hosts) as fixed, and Microsoft updated the MCT on October 28, 2025 to address host compatibility checks that previously caused the early termination. In practice, installing KB5067036 or receiving its changes via the November cumulative should eliminate the “we’re unable to run this tool” failure mode for affected scenarios.

Visible features rolling with KB5067036 (staged rollout)​

• Redesigned Start menu: a vertically scrollable All Apps surface, new Category/Grid/List view modes, and a cleaner navigation model.
• Taskbar and Lock Screen battery indicators: color‑coded battery states and optional percentage display in Settings.
• Copilot / Click to Do improvements: typed prompts, on‑screen translations, unit conversions, enhanced table detection and Copilot integration — some features are gated to Copilot+ hardware.
• Voice Access improvements (Fluid Dictation): on‑device small language models for punctuation/grammar improvements and filler-word suppression in supported locales.
• File Explorer Home: Recommended files, new hover quick-actions like “Open file location” and “Ask Copilot”, and StorageProvider APIs for cloud suggestions.

Important caveat: many of these experiences are server‑side gated and hardware-licensed; installing KB5067036 is the first step but does not guarantee immediate visibility of each feature on all devices. Microsoft’s staged rollout model enables incremental activation to reduce risk but increases variability in user experience.

---

Verification and cross‑checks​

To produce a reliable, verifiable account of this story, the following public artifacts were cross-checked:

• Microsoft’s Windows 11 / Windows 10 Release Health and Update History entries which document the MCT symptom, identify the affected MCT binary (26100.6584) and mark the issue as addressed when Microsoft updated the Media Creation Tool on October 28, 2025. These pages are the canonical technical statement from Microsoft.
• Independent reporting from reputable Windows and security outlets including BleepingComputer, Pureinfotech and WindowsReport which documented the KB preview (KB5067036), its build numbers for 24H2/25H2 and highlighted the MCT fix alongside feature previews. Cross-checking multiple outlets confirms the sequencing and the availability path (optional preview via Windows Update / Microsoft Update Catalog).
• Community reproductions and forum summaries that captured the user-facing symptom, practical impact, and the short-term mitigations recommended by Microsoft — this supports the characterization of the problem as real, narrow in scope, but painful for some workflows.

Where Microsoft’s public material lacked detail (for example, telemetry counts describing how many devices were affected), community reporting is useful but remains unverified. Microsoft has not published a device‑impact telemetry number for the MCT regression, so any reported counts in forums and social feeds should be treated as anecdotal until Microsoft publishes official telemetry.

---

Step‑by‑step: getting the fix or applying safe alternatives​

If you just want the MCT fix (recommended for early adopters and testers)​

1. Open Settings → Windows Update.
2. Click Check for updates.
3. Under “Optional updates available” look for KB5067036 (Preview) and click Download and install.
4. Reboot when prompted.
5. Verify your Media Creation Tool by re-downloading it from the official Microsoft Software Download page and running it; the early‑exit behavior should be resolved on updated hosts.

Note: Organizations can download KB5067036 from the Microsoft Update Catalog and deploy via WSUS, SCCM/ConfigMgr, Intune, or other management tooling.

If you do not want preview updates, or need an immediate workaround​

1. Download the official Windows 11 ISO (choose the Arm64 image if you need Arm media) from Microsoft’s Download Windows 11 page.
2. On a working x64 host (recommended), write the ISO to USB using a trusted media tool (Rufus, Ventoy, or a validated internal imaging tool).
3. For in‑place upgrades on eligible devices, use the Windows 11 Installation Assistant where appropriate.
4. Keep canonical ISO copies in your internal image library (store file checksums and enforce version control) to avoid ad hoc MCT runs during critical imaging tasks.

---

Analysis: strengths, risks, and what this incident exposes​

Strengths in Microsoft’s response and servicing model​

• Microsoft acknowledged the regression publicly in Release Health and provided immediate, safe mitigations (ISO downloads, x64 host creation) rather than leaving users guessing. The transparency in update history helps IT pros make informed deployment decisions.
• The preview KB model allows Microsoft to remediate narrow regressions and test new features in a contained way before broad Patch Tuesday distribution. That reduces the blast radius for large-scale deployments.

Risks and points of friction​

• Mixing fixes with feature previews: KB5067036 bundles a compatibility fix with numerous user-facing feature drops that are server‑side gated. That mix increases update complexity for support teams and may produce helpdesk volume when users install a preview package expecting visible changes that are not yet turned on. Several community posts highlight confusion and instances where preview updates created other unexpected side effects (e.g., UX or storage issues reported after installing preview KBs). These risks argue for piloted deployments in production environments.
• Architecture testing gaps: The MCT regression shows fragility in niche workflows (Arm64 on Arm64 hosts) that are less common but operationally critical for OEMs, imaging teams and developers. Testing matrices that underrepresent minority architectures or specialized workflows can let regressions slip into released artifacts. Enterprises with mixed-architecture fleets should retain fallback processes and canonical media.
• Preview updates can introduce new issues: Optional preview packages are useful, but community reports indicate some preview updates have introduced regressions on particular configurations. Admins must pilot preview KBs and maintain rollback plans.

Unverifiable or unconfirmed claims to treat cautiously​

• Exact numbers of affected devices and the precise fraction of Arm‑based users impacted remain undocumented publicly; Microsoft has not published detailed telemetry for the MCT regression. Any numeric claims beyond the observed community reproductions should be flagged as anecdotal until Microsoft releases telemetry.

---

Recommendations — practical guidance for readers​

For home users and enthusiasts​

• If you experienced the MCT failure and want the official fix: install KB5067036 via Settings → Windows Update (optional preview) or wait for the November Patch Tuesday cumulative if you prefer conservative updates.
• If you don’t want preview packages, use the Windows 11 ISO and Rufus / Ventoy to create bootable media on an x64 host; verify checksums and keep backups.

For power users, imaging teams and OEM technicians​

• Maintain a validated x64 staging host dedicated to media creation. Keep canonical ISOs (hashed, versioned) in your internal image library to avoid ad hoc tool regressions.
• Pilot KB5067036 in a test ring that reflects production hardware before rolling it into general deployment. Validate imaging, driver compatibility and recovery workflows such as WinRE and Startup Repair.

For IT administrators and enterprise teams​

1. Inventory workflows that rely on on-device media creation, legacy EVR playback, or WUSA installs from network shares.
2. Use controlled rings (WUfB, WSUS, Intune rings) to stage KB5067036 and confirm your critical scenarios.
3. Retain Known Issue Rollback (KIR) artifacts and rollback procedures for narrow regressions if Microsoft publishes them for your issue set.

---

Broader implications for Windows on Arm​

This incident is a reminder that as Windows expands its support for Arm platforms, tooling — even the officially supported convenience utilities — must be validated across architecture-specific workflows. The Arm ecosystem is growing rapidly, with more Copilot+ hardware and enhanced emulation making Arm a first-class platform for more users. Yet the majority of testing and usage remains x64-centric; when convenience pathways like on‑device media creation are assumed to be universal, narrow architecture regressions can produce outsized pain for those who depend on them (device refurbishers, field techs, individual Arm owners). The practical take-away is straightforward: build resilient pipelines that do not depend on a single on-device utility for critical media creation tasks.

---

Conclusion​

Microsoft’s KB5067036 preview update resolves the Media Creation Tool regression that caused the MCT binary 26100.6584 to fail on certain Arm64 hosts and some Windows 10 systems, and it does so while beginning a staged rollout of a set of user‑facing UI and Copilot enhancements. The fix is available today as an optional preview (installable from Settings → Windows Update or via the Microsoft Update Catalog) and will be folded into the regular Patch Tuesday cadence in November 2025, at which point the correction should reach mainstream servicing. Administrators and power users should pilot KB5067036 in a controlled ring, keep canonical ISOs and x64 media‑creation hosts available, and treat any reported impact numbers as unverified until Microsoft publishes telemetry.
The larger lesson is procedural rather than technical: don’t rely on convenience tools as the sole pillar of critical deployment workflows. Keep canonical artifacts, maintain a fallback imaging host, and run meaningful pilot rings that mirror your diversity of hardware — particularly when your fleet includes niche but important architectures such as Arm64.

---

---

Source: Research Snipers Microsoft Fixes Media Creation Tool Bug Blocking Windows 11 on Arm PCs – Research Snipers