Key changes and cautions
This is an optional preview rather than an urgent security fix; stability-focused systems can wait for the next regular cumulative update.
Microsoft · Windows 11 update
KB5120998 update details, changes and known issues
Windows 11 update KB5120998 · Released 2026-08-27
What is this update?
An optional Windows 11 preview update that delivers non-security quality improvements before the next regular cumulative update.
New features, security and compatibility
Problems fixed
No separately reviewed item is available for this section yet.
Known issues that remain
No separately reviewed item is available for this section yet.
Manually reviewed public feedback
Updatehey manually reviewed public discussions from 2026-08-08 to 2026-09-07 and retained 4 relevant sources.
Problem report · Font rendering issue after KB5120998
A public support-community report described severe font rendering problems after KB5120998 on Windows 11 25H2.
Reported environment: Windows 11 25H2
Reported response · KB5120998 Bluetooth report
An Alienware laptop user reported Bluetooth failure after the update and recovery after uninstalling KB5120998.
Reported environment: Alienware laptop
Problem report · KB5120998 DWM memory regression report
A Surface Pro 8 report with diagnostic details described abnormal dwm.exe memory growth after KB5120998. It remains a single-device report.
Reported environment: Surface Pro 8
Problem report · KB5120998 release discussion
Users reported mouse pointer appearance settings changing after installation, with Microsoft described as investigating.
Reported environment: Windows 11 24H2 and 25H2
These external posts are editorial references, not Updatehey installation reports. They do not automatically change the verdict, and a reported workaround is not a guaranteed fix.
Community-reported issues · automatic repeated signals
No repeating community signal is currently linked to this update.
Public Reddit/forum/support-community reports are early-warning signals, not proof of cause or a guaranteed fix. They remain separate from vendor-confirmed issues.
Documented responses
A response is shown with its evidence level. General guidance is not presented as a fix verified for this exact update.
When Windows will not boot after an update
Start with the lowest-risk Windows recovery options when a black screen or restart loop begins after an update.
1. Open Windows Recovery Environment
If Windows does not boot normally, open recovery options. A BitLocker recovery key may be required.
2. Uninstall the latest quality update
If the problem began immediately after updating, consider removing the latest quality update after confirming backups.
When a Windows update repeatedly fails to install
Begin with restart and built-in troubleshooting; use a repair reinstall only as a later official step.
1. Restart and check Windows Update again
Complete any pending restart and retry from Windows Update while recording a repeated error code.
2. Consider reinstalling the current Windows version
If basic troubleshooting fails, review Microsoft’s current-version reinstall procedure after confirming power and backups.
General checks before installing
These are general precautions unless a badge above says they were verified for this release.
Before installing
Back up important files, keep Windows recovery options available, and recheck official applicability and known issues.
Evidence freshness
Official evidence has been checked recently by the automated source monitor.
Evidence timeline
Recent official-document changes and community signals linked to this update. Official and unofficial evidence remain separated.
Official source changes
- 2026-10-15 08:17:40 · Microsoft release documentation
정규화된 본문 변경은 있으나 주요 문장 차이는 작음 · View original - 2026-10-15 08:17:40 · Microsoft release documentation
정규화된 본문 변경은 있으나 주요 문장 차이는 작음 · View original - 2026-10-15 08:17:40 · Microsoft release documentation
정규화된 본문 변경은 있으나 주요 문장 차이는 작음 · View original - 2026-10-15 08:17:40 · Microsoft release documentation
정규화된 본문 변경은 있으나 주요 문장 차이는 작음 · View original - 2026-10-14 20:17:40 · Microsoft release documentation
정규화된 본문 변경은 있으나 주요 문장 차이는 작음 · View original - 2026-10-14 20:17:40 · Microsoft release documentation
정규화된 본문 변경은 있으나 주요 문장 차이는 작음 · View original - 2026-10-14 20:17:40 · Microsoft release documentation
정규화된 본문 변경은 있으나 주요 문장 차이는 작음 · View original - 2026-10-14 20:17:40 · Microsoft release documentation
정규화된 본문 변경은 있으나 주요 문장 차이는 작음 · View original
CURRENT ASSESSMENT
Release historyNo Updatehey user sample yet
Check the latest supported release first.
A later release is available. Use this page for change history or rollback comparison, not as the current install recommendation.
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User reports
Field reports 0 · stable installs not enough data · confidence low
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Earlier and related updates
- KB5121003 · A cumulative update for Windows 11 24H2 and 25H2 containing the August 2026 security and quality fixes, including earlier cumulative changes. Released 2026-08-11
- KB5121000 · The August 2026 cumulative security update for Windows 11 26H1, combining vulnerability fixes and operating-system quality improvements. Released 2026-08-11
- KB5101684 · An optional cumulative preview of non-security quality fixes and feature improvements for Windows 11 24H2 and 25H2. Released 2026-07-28
- KB5121767 · An out-of-band cumulative Windows 11 update released outside the regular schedule to address a specific issue quickly. Released 2026-07-18
Related searches
KB5120998 Windows 11 24H2 25H2 preview issues optional update
Related official and general guides
Pause Windows updates · Uninstall a problematic update · Repair Windows Update
Frequently asked questions
Is KB5120998 safe to install?
Check the latest supported release first. A later release is available. Use this page for change history or rollback comparison, not as the current install recommendation.
Are there known issues with KB5120998?
No vendor-confirmed known issue is currently registered in Updatehey.
What should I do before or after installing KB5120998?
Before installing. Back up important files, keep Windows recovery options available, and recheck official applicability and known issues.
Update information changes as vendors publish new evidence. Back up important systems before installing.