Microsoft has quietly corrected a frustrating hiccup that left some users unable to create Windows installation media on Arm-based machines: the Media Creation Tool failure tied to build 26100.6584 is listed as fixed in the October preview cumulative update KB5067036, which also bundles a broad set of feature previews and reliability improvements for Windows 11, versions 24H2 and 25H2.
The timing amplified the noise: the regression appeared in the weeks leading up to Windows 10’s end-of-support deadline (October 14, 2025), a period when many users and administrators were preparing last‑minute migrations, recovery sticks, and clean installs. That made the breakage more visible and more painful for some workflows than it might have been otherwise.
The package is notable because it mixes:
Source: Windows Report KB5067036 Fixes Broken Media Creation Tool in Arm-based Windows 11 25H2 PCs
Background
What broke, when, and why it mattered
In late September 2025 Microsoft shipped an updated Windows 11 Media Creation Tool (MCT) binary identified in community reporting as version 26100.6584. Shortly after that release, users running the tool on certain hosts — including some Arm64 and Windows 10 (22H2) machines — reported that the executable would prompt for UAC, flash the Windows logo briefly, then exit silently with the unhelpful message: “We’re not sure what happened, but we’re unable to run this tool on your PC.” Microsoft added that behavior to its Release Health / update‑history documentation and recommended users download ISOs directly while a fix was prepared.The timing amplified the noise: the regression appeared in the weeks leading up to Windows 10’s end-of-support deadline (October 14, 2025), a period when many users and administrators were preparing last‑minute migrations, recovery sticks, and clean installs. That made the breakage more visible and more painful for some workflows than it might have been otherwise.
Scope and immediate mitigations
Microsoft characterized the issue as a host‑OS compatibility problem. The developer guidance stressed that the MCT was not intended to create Arm64-targeted media from an Arm64 host in that particular implementation, and the regression compounded those limitations by aborting on some Windows 10 hosts as well. Short-term, Microsoft suggested two safe mitigations: download the official Windows 11 ISO from Microsoft’s Software Download page and write it to USB with a trusted tool, or run the Windows 11 Installation Assistant for an in-place upgrade on eligible machines. These alternatives avoided the broken single-file convenience path until a remedial update could be issued.What KB5067036 actually is (overview)
KB5067036 is a non‑security, optional preview cumulative update released to Windows 11, versions 24H2 and 25H2, delivered as OS builds 26100.7019 (24H2) and 26200.7019 (25H2) in the October 28, 2025 release. This preview packaging is Microsoft’s monthly channel for testing non‑security fixes and a selection of feature drops before those items are folded into the regular Patch Tuesday servicing stream.The package is notable because it mixes:
- A targeted compatibility fix (the MCT failure on Arm64/Windows 10 hosts).
- Visible user‑facing UI changes, such as a redesigned Start Menu and new taskbar/lock‑screen battery indicators.
- On‑device Copilot and accessibility improvements — enhancements to Click to Do, Voice Access (fluid dictation), and File Explorer that are staged to roll out gradually and in some cases gated to Copilot+ hardware.
The Media Creation Tool fix — technical snapshot
What Microsoft fixed
The release notes explicitly list the MCT behavior — the tool (version 26100.6584) failing to run on certain Arm64 hosts and some Windows 10 (22H2) configurations — as a known issue that the update addresses. Practically, KB5067036 contains a remediation that corrects the MCT’s host‑compatibility checks and replaces the problematic binary, removing the early termination condition that caused the silent exits on affected hosts. Microsoft’s documentation and the KB entry identify the affected tool build and state that a fix was included in the preview update.What remains important to test
- The MCT fix addresses the observed bootstrap crash/early termination symptom, but Microsoft’s public advisory did not include telemetry showing how many users were affected; that number remains unpublished. Treat any numerical impact claims as unverified unless Microsoft publishes them.
- Because some of the changes are gated server‑side, deploying KB5067036 does not guarantee immediate exposure to the redesigned Start Menu, Copilot expansions, or other progressive features; those are enabled gradually once Microsoft flips related server flags.
What else is in KB5067036 (visible user features)
KB5067036 is more than a binary fix. For end users, the update preview begins the rollout of several visible UI and on‑device AI changes:- Redesigned Start Menu: A single, scrollable main surface that places the All apps list front and center, new Category and Grid view modes, and the ability to hide or collapse sections like Pinned and Recommended. This aims to simplify navigation and speed app discovery.
- Color‑coded battery indicators on the taskbar (green/yellow/red) with an optional percentage display in Settings — the same visual language is rolling to the Lock screen in phased fashion.
- Copilot / Click to Do enhancements (targeted at Copilot+ PCs): inline typed prompts in Click to Do, on‑screen translations, unit conversions, better table and selection handling, and improved integration into File Explorer. Many of these features rely on on‑device models and hardware licensing, so availability depends on hardware eligibility and server‑side rollout.
- Voice Access — Fluid Dictation: on‑device small‑language‑model (SLM) powered dictation that improves punctuation, grammar correction, and filler‑word suppression in real time for supported locales.
- File Explorer Home improvements: recommended files for personal/local accounts, hover quick‑actions (for example “Open file location” and “Ask Copilot”), and StorageProvider APIs for cloud providers to feed suggestions.
Practical guidance — how to get the fix and safe workarounds
If your Media Creation Tool failed
- Install KB5067036: open Settings > Windows Update > Check for updates. If KB5067036 appears under "Optional updates available," click Download and install and reboot when prompted. Admins can pull the standalone package from the Microsoft Update Catalog for controlled deployment.
- If you prefer not to install optional preview updates, use the official ISO workaround:
- Download the appropriate Windows 11 ISO from Microsoft’s Software Download page (choose Arm64 only if you need Arm‑targeted media).
- Use a trusted USB writer (Rufus, Ventoy, or Microsoft’s guidance using File Explorer and setup.exe) to write the ISO to a bootable USB.
- Verify the ISO hash if Microsoft provides it — checksum verification reduces the chance of corrupted or tampered images.
- If you must create Arm64 installation media and your Arm host’s MCT fails, use an x64 (Intel/AMD) host to build Arm64 bootable media from the Arm64 ISO — Microsoft explicitly described this as a practical workaround while the Arm‑host path was fixed.
Step‑by‑step: create a bootable USB from an official ISO (safe, reproducible)
- Go to Microsoft’s Download Windows 11 page and choose Download Windows 11 Disk Image (ISO). Select the correct edition and architecture.
- On an available PC (recommended: x64 host for Arm64-targeted ISOs), download the ISO and verify a checksum if provided.
- Use Rufus (run as administrator) or Windows’ built-in mounting to either write the ISO to USB or run setup.exe for an in‑place upgrade. In Rufus:
- Partition scheme: GPT
- Target system: UEFI (non‑CSM)
- File system: NTFS (if required by the ISO)
- Click Start and let Rufus write the image.
- Boot the target device from the USB, choose Upgrade or Custom Install, and follow the installer prompts. Back up data first.
Critical analysis — strengths, trade-offs and risks
Strengths: rapid triage, transparent advisory, and bundled fixes
Microsoft’s response timeline — documenting the MCT failure in Release Health, publicly recommending safe mitigations, and shipping a corrected binary inside a preview cumulative update — is a textbook triage: identify the regression, publish an advisory, offer workarounds, and deliver a fix in a controlled preview channel. The mixed packaging approach also lets Microsoft fold multiple small feature improvements and quality fixes into a single testable update for Release Preview insiders, shortening validation cycles.Trade‑offs and risks
- Timing risk: The regression landed in a high‑pressure migration window (Windows 10 EoS). Regardless of the absolute number of impacted devices, the perceived severity rises when a convenience tool breaks at a hard lifecycle milestone. Community noise and media coverage amplified user frustration.
- Feature gating causes confusion: The KB mixes a bug fix with many server‑gated features. Installing the KB may not immediately surface UI changes for every user, which generates helpdesk volume and encourages unsafe community-driven methods to force features on. Gradual rollouts require clearer user messaging.
- Architecture testing gaps: The incident underlines fragility in niche, architecture‑specific workflows (Arm64 on Arm hosts). Even though Arm workflows are a minority, they are critical for OEM imaging, developer labs, and device builders. Testing matrices must better represent these operational edge cases.
Unverified or uncertain points
- Microsoft has not published public telemetry on the number of devices affected by the MCT regression. Any published counts in community posts or outlets should be treated as unverified until Microsoft releases official telemetry.
Recommendations for administrators and power users
- Pilot KB5067036 in a controlled ring first. Validate imaging, playback, and update‑delivery workflows representative of your environment (x64, Arm64, legacy playback stacks).
- Maintain a canonical ISO repository (hashed and signed) in your internal update library instead of relying on ad hoc MCT runs from diverse hosts. Use WSUS, SCCM/ConfigMgr, or Intune distribution for predictable deployments.
- Keep an x64 staging host available for media creation if your organization uses Arm64 test hardware. This is a low‑cost, high‑value hedge until tooling is proven on Arm hosts.
- Use Known Issue Rollback (KIR) artifacts where Microsoft publishes them for narrow regressions, and review KIR Group Policy deployment paths for fast enterprise remediation if needed.
- Avoid forced or unsupported bypasses (e.g., TPM/Secure Boot removals) for production machines. Unsupported configurations may block future updates or create compliance problems. If you must use bypass techniques for legacy hardware, isolate those devices and document the tradeoffs.
Security and compliance considerations
- Do not download ISOs from untrusted third-party mirrors. Always use Microsoft’s official ISO images or trusted internal copies to minimize the risk of tampered images. Verifying checksums where available is a simple and effective safeguard.
- Be cautious about community tools or registry tweaks that force server‑gated features to appear. Those methods may circumvent telemetry, degrade stability, and complicate support or compliance audits. Prefer official release channels for enterprise systems.
Other known issues to watch (context)
KB5067036 fixes a collection of regressions, but the servicing cycle around 24H2/25H2 exposed multiple narrow issues earlier in October 2025 — for example, a WinRE / recovery environment bug and some HTTP.sys/IIS regressions documented in Microsoft channels and reported by outlets. Admins who manage critical media, recovery, or server workloads should monitor release‑health and official KB pages for related mitigations and KIR artifacts before broad deployment.What to monitor next
- Watch for the Patch Tuesday packaging that folds KB5067036’s corrections into the regular cumulative updates; that’s the route by which the MCT fix will reach mainstream servicing channels.
- Track Microsoft’s Release Health and update‑history pages for any follow‑up advisories, telemetry disclosures, or Known Issue Rollback artifacts that apply to your environment.
- If your organization relies on legacy media pipelines or specialized hardware (capture cards, EVR players), validate those paths on a test ring before accepting 25H2 or preview updates.
Conclusion
KB5067036 demonstrates a pragmatic but imperfect reality of modern Windows servicing: fixes and new features are bundled and validated in preview channels to accelerate iteration, but the same cadence can magnify user pain when an outwardly simple convenience tool breaks at a sensitive moment. Microsoft has documented the MCT failure, provided safe workarounds (official ISOs, Installation Assistant, x64 host creation for Arm64 media), and delivered a fix in the October preview update. Organizations and power users should pilot the update, keep canonical ISO images, retain an x64 media‑creation host, and monitor Microsoft’s Release Health for further follow‑up. The most important operational takeaway is simple: when convenience tools fail, stable, verifiable artifacts (canonical ISOs and controlled deployment pipelines) remain the safest path forward until tooling is fully validated.Source: Windows Report KB5067036 Fixes Broken Media Creation Tool in Arm-based Windows 11 25H2 PCs
