The KB5120998 mouse reset bug that has been reverting cursor personalisation settings since the August 2026 preview update dropped affects only non-English Windows 11 installations, Microsoft has confirmed. The company updated its Windows release health dashboard on Tuesday to narrow down the scope of the issue, almost a week after the update first shipped.
The KB5120998 update, released on 27 August 2026, is an optional, non-security preview that brings improvements to the Start menu, the taskbar, and Windows search on devices running Windows 11 versions 25H2 and 24H2. Users on affected systems reported that mouse cursor personalisation settings (including cursor style and cursor animations) were changing or resetting automatically after installation, with no obvious way to restore them. The bug was confirmed by Microsoft the day after the update’s release.
What Microsoft’s investigation found about the KB5120998 mouse reset bug
In its Tuesday update to the health dashboard, Microsoft pointed squarely at localisation as the culprit. ‘Our investigation indicates that this issue is caused by code components used in non-English Windows installations. In impacted locales, these settings will fail to load, causing a default to be used instead,’ the company said. That is a fairly precise diagnosis: it is not a general flaw in the settings pipeline, but a failure specific to how certain language and locale configurations handle the relevant code components at load time.
Microsoft’s original statement, issued when the bug was first confirmed, described the problem in broader terms: ‘Following installation of Windows updates released August 27 2026 (KB5120998) and later, mouse personalization settings are being reverted to certain standard settings. This includes cursor and cursor animations that are selected in the Mouse Properties options under Windows.’ The Tuesday update effectively tells English-language users they can stand down.
How to avoid the update, and what else went wrong
Because KB5120998 is an optional preview update, most users will not receive it automatically. Installation requires manually clicking ‘Download and install’ in Windows Update. There is a catch, however: if the ‘Get the latest updates as soon as they’re available’ toggle is switched on, the preview update will install without prompting. Users who want to avoid the bug until a fix arrives should check that setting is off.
The cursor reset is not the only problem to surface alongside this update. On Wednesday, Microsoft also acknowledged that Windows desktop settings will be lost or reset on some devices after installing the KB5120998 preview update, adding a second known issue to what was supposed to be a quality-of-life release.
Neither issue exists in isolation. Microsoft has been dealing with a run of mouse and input-related problems on Windows devices. In October, it pushed emergency updates to resolve a known issue that rendered the Windows Recovery Environment unusable by disabling USB mice and keyboards entirely, the kind of failure that leaves users unable to complete a recovery operation at the moment they need it most. More recently, Microsoft said it is investigating a separate bug that causes the mouse pointer to vanish for some users of classic Outlook when moving it over the interface.
Taken together, the pattern is a reminder that preview updates, even those labelled optional and non-security, carry real risk when they interact with the broad diversity of locale configurations, hardware setups, and software stacks across the Windows ecosystem. Microsoft has not yet announced a timeline for a fix to the KB5120998 mouse reset bug, but given that the investigation has now identified the cause, a remediation update targeting non-English locales is the expected next step.
