Windows 11 25H2 Rollout: Four Key Regressions and Mitigations

Microsoft’s staged rollout of Windows 11 version 25H2 arrived as a quiet, low‑friction enablement package but shipped with four confirmed, narrowly scoped regressions that are already being tracked and mitigated — problems that matter a great deal if your workflows depend on legacy media playback, scripted .msu deployments from network shares, SMBv1/NetBIOS file‑sharing paths, or on‑device ARM64 media creation.

Background / Overview​

Windows 11 25H2 is being delivered primarily as an enablement package, flipping features already present in the 24H2 servicing stream rather than replacing the whole OS image. That delivery model makes the update small and fast for most users, but it also means any servicing regressions introduced earlier in 2025 can be carried forward into 25H2. Major outlets and Microsoft’s own Release Health pages confirm the enablement‑package model and explain why 25H2 feels incremental rather than transformative.
Microsoft has published a compact known‑issues list for 25H2 that currently highlights four operational problems: (1) protected/DRM playback failures in apps that use the legacy Enhanced Video Renderer (EVR) with HDCP enforcement; (2) WUSA (.msu) installers failing with ERROR_BAD_PATHNAME when run from network shares containing multiple .msu files; (3) SMBv1/NetBIOS file‑sharing connections that may fail after recent September servicing; and (4) the Media Creation Tool not running as expected on Arm64 hosts — specifically, Arm64 devices cannot create Arm64 installation media from themselves. These four items are narrow in scope but high in impact for specific user groups.
This article summarizes the technical facts, verifies the claims against Microsoft and independent reporting, analyzes the practical impact for consumers and IT professionals, and provides concrete, actionable mitigations and deployment guidance.

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What Microsoft and industry reporting confirm​

The four confirmed issues (short form)​

• Protected playback failures in EVR/HDCP/DRM scenarios (Blu‑ray, DVD and some digital‑TV/capture apps).
• WUSA (.msu) installers may return ERROR_BAD_PATHNAME when run from a network share containing multiple .msu files (affects devices updated since May 28, 2025 / KB5058499).
• SMBv1 (NetBIOS over TCP/IP / NetBT) file‑share connections can fail after September updates; mitigation: allow TCP/445 to force SMB to use TCP rather than NetBT.
• Media Creation Tool won’t run on Arm64 hosts to create Arm64 media (tool remains usable on x64 hosts for x64 media).

Each of the above is listed or described in Microsoft’s Windows 11 25H2 Release Health / Update History pages and corroborated by multiple independent outlets and community reports. Where possible Microsoft has staged targeted mitigations (for example, a Release Preview remediation for the EVR playback regression) and used Known Issue Rollback (KIR) or guidance for managed environments on the WUSA problem.

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Deep dive: Protected playback (EVR / HDCP / DRM)​

What broke — and why it matters​

Some Blu‑ray, DVD and digital TV applications that rely on Enhanced Video Renderer (EVR) with HDCP enforcement or OS‑level DRM for digital audio may fail to play protected content. Symptoms observed in the field include copyright errors, black screens, abrupt stops, and repeated interruptions during playback. Streaming services and modern UWP/browser DRM flows are widely reported as not affected because they use newer rendering paths and app‑managed DRM.
EVR is a legacy rendering path used by many long‑lived media and tuner applications; protected playback relies on an end‑to‑end handshake (app → OS DRM stack → GPU driver → display/capture device). If any link in that chain no longer meets tightened platform expectations, the platform will “fail closed” — blocking playback rather than risking content leakage. That is intended behavior from a content‑protection standpoint, but it produces a hard break for legacy software that still depends on EVR semantics.

What caused it (timeline and KBs)​

Community tracing linked the regression to an August 29, 2025 preview update (KB5064081) that was folded into the September 9, 2025 cumulative (KB5065426 / OS Build 26100.6584). Microsoft acknowledged the problem and staged a targeted remediation to the Release Preview channel as KB5065789 in mid‑September; that remediation addresses many EVR/HDCP failures while Microsoft continues work on remaining DRM audio scenarios.

Mitigations and best practices​

• If you run legacy Blu‑ray/DVD or tuner/capture applications that must play protected content, do not install the implicated preview/cumulative updates or 25H2 on production playback machines until the remediation is validated on your hardware.
• If already affected, consider using a different playback pipeline (a modern UWP/browser client), hardware playback devices, or a separate, unaffected PC for protected media. Some vendors released updated players or guidance; check vendor pages and driver updates.
• For enterprise or institutional deployments (lecture capture, digital signage, broadcast ingest), stage 25H2 to a test ring representing your legacy workflows and validate playback end‑to‑end before broad deployment. Use rollback procedures if necessary.

Where Microsoft stands​

Microsoft’s Release Health entry marks this issue as partially resolved: many EVR/HDCP problems were addressed by the preview remediation (KB5065789), but some audio DRM scenarios still await a permanent fix. Microsoft recommends installing the latest updates once released and monitoring the Release Health page for status changes.

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The WUSA / .msu network‑share regression​

The symptom​

Administrators who rely on the Windows Update Standalone Installer (wusa.exe) to apply .msu packages from network shares may encounter ERROR_BAD_PATHNAME when the share contains multiple .msu files. The issue is reproducible: installing the same .msu locally or moving it to a share with only a single .msu avoids the error. This primarily affects scripted/manual enterprise workflows rather than typical consumer update flows.

Root and timeline​

Microsoft traced the regression to servicing changes beginning with updates released May 28, 2025 (notably KB5058499) and later cumulative servicing. Because WUSA / WUA APIs exercise different code paths than online Windows Update or WSUS, the regression displayed in network‑share scenarios while many consumer update paths were unaffected. Microsoft mitigated consumer exposure using Known Issue Rollback and published Group Policy artifacts for managed environments to accelerate remediation.

Practical mitigations​

• Copy .msu files locally and run WUSA from the local disk. This is the simplest and most reliable workaround.
• For managed environments, apply Microsoft’s KIR Group Policy or KIR MSI to expedite rollback behavior on affected devices. Use automation to copy installers locally in your deployment scripts until the servicing fix is broadly distributed.
• Validate WSUS/SCCM flows separately; different update channels may show different behaviors. If you rely on remote script installation, consider using DISM to add CAB packages after extracting the .msu locally.

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SMBv1 / NetBIOS over TCP/IP (NetBT) failures​

The symptom and scope​

After September servicing, some systems using the deprecated SMBv1 protocol via NetBIOS over TCP/IP (NetBT) failed to connect to shared files and folders. The issue affects SMBv1 connections that rely on NetBT; systems using SMBv2 or SMBv3 are not affected. Microsoft explicitly notes the protocol is deprecated and not installed by default in modern Windows builds.

Mitigation​

Microsoft’s recommended workaround is to allow traffic on TCP port 445 so the client and server will use TCP rather than NetBT, which allows the SMB connection to resume. Administrators should treat this as a stopgap: the enduring fix is migration away from SMBv1 to modern SMBv2/SMBv3 implementations or updating legacy devices that require SMBv1.

Operational considerations​

• SMBv1 is insecure and deprecated; this regression gives organizations one more reason to accelerate migration of embedded devices, NAS units, or legacy appliances that still require SMBv1.
• If immediate migration is impossible, test the TCP/445 workaround in a controlled environment, and document the temporary network rule for security review.

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Media Creation Tool on Arm64 hosts​

The issue​

Microsoft documented that the Media Creation Tool (version tied to the 25H2 build family) may not run correctly on Arm64 devices when used to create Arm64 installation media. Error messaging presented to users can be generic — e.g., “We’re not sure what happened, but we’re unable to run this tool on your PC.” Microsoft’s note clarifies that the Media Creation Tool is not supported for creating Arm64 media from an Arm64 host; however, Arm64 hosts normally could create x64 media — that pathway was reported to be affected in this roll‑out.

Practical effect​

This is a narrow problem: most users don’t create ARM64 installation media from an ARM device. The major practical consequence is for developers, OEM techs, or IT staff using on‑device tooling to produce Arm64 installers. The workaround is to use an x64 (Intel/AMD) machine to create the Arm64 media until Microsoft patches the tool. Independent outlets and Microsoft’s update history both document the issue and advise the same mitigation.

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Cross‑verification and reliability of the claims​

Key claims in this story are cross‑verified against Microsoft’s Release Health / Support pages and multiple reputable independent outlets and community reporting. Microsoft’s known‑issues pages list the EVR playback regression and the WUSA network share failure, and they describe mitigation steps or remediation staging (e.g., KB5065789 for EVR). Independent technology publications and community forums reproduced the symptoms and reported Microsoft’s guidance and KIR mitigations. Where Microsoft has staged fixes (Release Preview, KIR) those actions are documented on the Release Health page and in preview KB notes.
If you need the most recent nuance for a particular KB, build number, or remediation timeline, always consult Microsoft’s official Release Health / Update History entries for Windows 11 25H2 and the specific KB pages — Microsoft updates those pages as fixes are validated and broadly released.

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Practical guidance: who should upgrade now, and who should wait​

For everyday consumers (streaming, web, basic productivity)​

Most consumers who use modern streaming apps (Netflix, Prime, Disney+, browser‑based video) and who do not run legacy EVR‑based media software are unlikely to encounter these regressions. 25H2 is small, delivers the support‑reset that comes with a new feature update label, and will be offered gradually via Windows Update. Standard advice applies: ensure you have a current backup, update drivers, and prefer staged rollouts over forced immediate installation.

For HTPC owners, Blu‑ray/DVD collectors, broadcast and capture users​

Delay. If your playback/capture workflows use legacy DirectShow/EVR pipelines, do not accept 25H2 or the implicated servicing updates on production hardware until Microsoft’s remediation has been validated for your exact player + GPU driver + tuner combination. Consider using separate, validated hardware for protected playback in the meantime.

For IT administrators and enterprises​

Pilot first. Run 25H2 in a controlled ring that represents legacy workflows: WUSA‑based installs, SMBv1 dependencies, and any Arm64 media creation processes. If you employ WUSA from network shares, update deployment scripts to copy .msu files locally or use DISM/WSUS channels. Apply KIR Group Policy artifacts where Microsoft published them to speed mitigation on managed devices. Document and test the TCP/445 SMB workaround if you must support SMBv1 devices temporarily, but plan accelerated migration away from SMBv1.

For device builders and imaging teams using Arm64 hardware​

Use an x64 host to create Arm64 media until Microsoft patches the Media Creation Tool behavior. Track Microsoft’s update history for remediations and test any produced media in an isolated validation environment.

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Step‑by‑step mitigations (concise)​

• Identify risk: run winver and note build numbers (24H2 vs 25H2 + OS build). Test critical playback and update‑deployment paths on a non‑production test device first.
• For EVR playback problems: avoid installing the implicated preview/cumulative updates on playback machines and apply the Release Preview remediation once validated; use alternate playback clients or hardware players in the meantime.
• For WUSA/.msu installations: copy .msu locally and run wusa.exe from disk; for managed fleets apply Microsoft’s KIR Group Policy or KIR MSI; update deployment scripts accordingly.
• For SMBv1 failures: allow TCP/445 to force TCP transport as a temporary measure; prioritize migration to SMBv2/v3.
• For Media Creation Tool on Arm64: create Arm64 media on an x64 host until the tool is fixed; track Microsoft’s update history for resolution.

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Strengths, risks and the broader picture​

Notable strengths​

• Microsoft’s enablement‑package approach keeps installs small and fast for most users, reducing downtime and simplifying the upgrade experience for the majority.
• Microsoft’s Release Health process and Known Issue Rollback (KIR) mechanisms allow targeted mitigation without rolling back security improvements globally. The company staged a targeted remediation for EVR playback in Release Preview (KB5065789), demonstrating a surgical fix approach for narrow regressions.

Significant risks and trade‑offs​

• The servicing model that enables fast updates also creates the possibility that a single servicing change affects multiple downstream scenarios, particularly legacy APIs and enterprise toolchains. Changes that tighten protected‑media handshakes or adjust update‑installation parsing can break long‑standing workflows with real operational consequences.
• Narrow, high‑impact regressions are harder to spot in broad beta programs because the affected population (HTPC users, legacy imaging workflows, SMBv1-dependent devices) is small relative to Windows’ total install base — yet those users can suffer productivity or service outages.

What to watch next​

• Watch Microsoft’s Windows 11 25H2 Release Health / Update History pages closely for official remediation rollouts and KIR activations. Confirm GPU driver updates from vendors (NVIDIA, AMD, Intel) because protected playback outcomes are often driver‑dependent.
• For enterprises, track KIR Group Policy artifacts and test the mitigations in a preproduction ring before broad adoption.

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Final verdict and recommended posture​

Windows 11 version 25H2 is an incremental, enablement‑package release designed to refresh the servicing timeline and deliver a modest set of improvements with minimal disruption for the majority of users. However, the appearance of four verified, narrow regressions at launch is a practical reminder that even incremental servicing changes can have outsized effects on legacy or specialized workflows.

• If you are a mainstream consumer using modern streaming apps and standard productivity software, upgrading to 25H2 is reasonable once your device is offered the enablement package; keep your drivers current and maintain backups.
• If your environment depends on legacy EVR playback, WUSA‑from‑share deployments, SMBv1 devices, or Arm64 self‑serving media creation, adopt a conservative approach: pilot 25H2, apply the specific mitigations described above, and delay broad deployment until Microsoft confirms fixes for your scenario.

Microsoft’s quick staging of targeted fixes (Release Preview remediation, KIR artifacts) shows the company is actively triaging the problems. Still, the practical path for sensitive users and IT teams is clear: test first, upgrade selectively, and fallback to local‑copy or alternate workflows where necessary until remediations are validated in your environment.

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This is a live issue: check Microsoft’s Windows 11 25H2 Release Health page and the specific KB pages for the latest remediation status and any new guidance before changing your deployment stance.

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Source: Faharas News Windows 11 25H2 Update Launches with Four Known Issues for Users - Faharas News