# Microsoft Probes Windows 11 KB5120998 Bug Resetting Mouse Settings on Non-English Systems

Source: TechNewsList (https://technewslist.com)
Canonical URL: https://technewslist.com/en/article/microsoft-probes-windows-11-kb5120998-mouse-reset-bug-on-non-english-systems-202
Section: Software (https://technewslist.com/en/software)
Author: TechNewsList
Language: en
Published: 2026-09-03T17:38:20.383+00:00
Updated: 2026-09-03T17:38:20.541546+00:00

> Microsoft acknowledged on September 3, 2026, that an issue in optional preview update KB5120998 automatically resets mouse pointer personalization settings exclusively on non-English Windows 11 PCs.

## TL;DR
- Microsoft confirmed that optional preview update KB5120998 causes custom mouse settings to reset to default values.
- Investigation reveals the bug is isolated entirely to non-English language Windows 11 installations.
- Affected users cannot save custom pointer speeds, cursor animations, or visual schemes across system reboots.

## Key points
- The issue impacts systems running Windows 11 version 25H2 and version 24H2 that installed the August 2026 preview update.
- The failure is traced to localized Multilingual User Interface (MUI) parsing components failing to load custom user registry keys.
- Because KB5120998 is an optional non-security preview, users who disable automatic preview installs remain unaffected.
- Microsoft is preparing an automated Known Issue Rollback (KIR) fix that resolves the issue without requiring patch uninstallation.
- IT administrators can deploy temporary group policies or restore default English display language packages as a workaround.

## What happened

Microsoft officially confirmed on September 3, 2026, that a newly discovered operating system bug causes custom mouse personalization settings to automatically revert to default configurations after installing optional preview update KB5120998. The anomaly, initially reported by users following the update's release in late August, alters mouse cursor schemes, pointer movement speed, pointer trails, and custom cursor animations. In an updated advisory published on the Windows Release Health dashboard, Microsoft's engineering team revealed that the bug does not affect all installations uniformly, but is isolated strictly to non-English language installations of Windows 11 versions 25H2 and 24H2.

According to user reports across enterprise support forums and the Windows Feedback Hub, affected workstations discard user modifications made within the classic Mouse Properties dialog or the modern Settings app upon every system reboot or user account sign-off. When users attempt to reapply custom cursor files (.cur and .ani files) or adjust pointer acceleration thresholds, the operating system fails to persist the values, immediately defaulting back to the standard white Windows cursor. Microsoft confirmed that it has opened an active service investigation to deploy a rapid mitigation.

## Why it matters

While a mouse pointer reset may superficially appear to be a minor aesthetic inconvenience, custom pointer configurations are critical accessibility features for millions of users worldwide. Individuals with visual impairments, low contrast sensitivity, or motor control challenges frequently rely on enlarged, high-contrast, or brightly colored mouse pointers and modified tracking speeds to navigate their computer desktops effectively. For these users, an involuntary regression to low-visibility default pointers severely degrades device usability and impairs workplace productivity.

From an enterprise IT operations perspective, the bug highlights the persistent risks associated with deploying optional cumulative preview updates across international fleet environments. Multinational corporations and localized enterprise environments running non-English Windows 11 images face unexpected helpdesk ticket spikes and user complaints. The incident reinforces the importance of conservative update rings within enterprise endpoint management tools like Microsoft Intune and Windows Server Update Services (WSUS).

## Technical details

Microsoft's technical analysis indicates that the fault is rooted in localized Multilingual User Interface (MUI) resource parsing modules updated as part of KB5120998. Under normal operation, when Windows boots, the user profile subsystem queries the registry hive under `HKEY_CURRENT_USER\Control Panel\Cursors` and loads customized pointer paths and velocity multipliers. However, in non-English locale builds, the updated MUI string resolver encounters an unhandled exception when evaluating localized resource identifiers, triggering a defensive fallback routine that resets the registry keys to standard system defaults.

![Windows Registry Editor interface displaying user input configuration keys](https://rkhynbcsbnkkcwgexzwg.supabase.co/storage/v1/object/public/media/api/1788457091766-0qg6ne-microsoft-probes-windows-11-kb5120998-mouse-reset-bug-on-non-english-systems-202-inside-1-179087d614.webp)
*Windows 11 Registry Editor interface displaying user input configuration keys and mouse scheme parameters.*

Because KB5120998 is an optional non-security preview release, it is not pushed automatically to managed devices unless users or administrators have explicitly clicked "Download and install" or enabled the toggle labeled "Get the latest updates as soon as they're available." Devices operating in standard English (United States) locales do not trigger the MUI exception, explaining why the issue escaped automated pre-release test suites that primarily evaluate default English runtime builds.

![Windows 11 Advanced Startup Settings and recovery troubleshooting menu](https://rkhynbcsbnkkcwgexzwg.supabase.co/storage/v1/object/public/media/api/1788457093604-uud68l-microsoft-probes-windows-11-kb5120998-mouse-reset-bug-on-non-english-systems-202-inside-2-30ea28f3aa.webp)
*Windows 11 Advanced Startup Settings screen utilized by system administrators during recovery diagnostics.*

## Market / industry impact

This localization regression comes amid increased industry scrutiny regarding Windows update stability and quality assurance processes. Microsoft has previously contended with high-profile peripheral glitches, including an emergency update cycle in October that temporarily disabled USB mouse and keyboard inputs within the Windows Recovery Environment (WinRE), as well as cursor disappearance bugs in classic Outlook. Recurring input stack regressions have prompted enterprise system administrators to call for more comprehensive multi-language automated regression testing before preview builds are promoted to the public.

For international software vendors that produce custom accessibility drivers and specialized peripheral management suites, the bug introduces temporary compatibility friction. Third-party mouse configuration utilities that interface with Windows cursor APIs find their settings overwritten on reboot, leading end users to erroneously assume the third-party hardware software is malfunctioning.

## What to watch next

Microsoft stated that it is developing an automated Known Issue Rollback (KIR) update to resolve the localized MUI component fault. A Known Issue Rollback allows Microsoft's cloud servicing pipeline to remotely disable the specific problematic code path on consumer and unmanaged business devices within 24 to 48 hours, without requiring users to manually uninstall the broader KB5120998 cumulative update package.

Enterprise administrators managing domain-joined workstations can apply special Group Policy objects provided by Microsoft to disable the faulty component across their organizational units immediately. The permanent code fix is scheduled to be bundled into the mandatory Patch Tuesday cumulative security update arriving in mid-September 2026, which will resolve the underlying localization parsing logic across all supported Windows 11 editions.

## Sources

- [BleepingComputer Enterprise Support](https://www.bleepingcomputer.com/news/microsoft/microsoft-kb5120998-mouse-reset-bug-affects-only-non-english-pcs/) - In-depth technical report tracking the root cause analysis, affected Windows versions, and official company disclosures.
- [Microsoft Support Knowledge Base](https://support.microsoft.com/en-us/help/5120998) - Official patch documentation detailing the scope of preview update KB5120998 and documented known issues.
- [Windows Release Health Dashboard](https://learn.microsoft.com/en-us/windows/release-health/status-windows-11-25h2) - Official engineering status tracking confirming the active investigation and Known Issue Rollback deployment timeline.

Mentions: Microsoft, Windows 11, KB5120998, Windows Release Health, Known Issue Rollback, MUI

## Sources
- [BleepingComputer Enterprise Support](https://www.bleepingcomputer.com/news/microsoft/microsoft-kb5120998-mouse-reset-bug-affects-only-non-english-pcs/)
- [Microsoft Support Knowledge Base](https://support.microsoft.com/en-us/help/5120998)
- [Windows Release Health Dashboard](https://learn.microsoft.com/en-us/windows/release-health/status-windows-11-25h2)