Microsoft acknowledges the KB5120998 black desktop on Windows 11 (September 2, 2026)
Chapters
What was added on September 2
Microsoft's wording in the new entry is that following installation of Windows updates released August 27, 2026 and later, some Windows Desktop settings fail to load, resulting in desktop backgrounds displaying as a solid black color. It adds that it is possible other desktop settings may be affected, such as slideshow settings or contrast themes.
Five days passed between the update shipping on August 27, 2026 and this entry, and four days between the cursor half of the same regression getting its own entry on August 28, 2026 and the wallpaper half getting this one. Until September 2 the black desktop was a pile of confirmed user complaints with no matching Microsoft record, which is how Windows Latest described it on August 29, 2026.
I covered that state of play in the August 29 post. What is new today is the record, not the symptom.
TL;DR
Microsoft acknowledged on September 2, 2026 that after KB5120998 some Windows 11 desktop settings fail to load and the background shows as a solid black color, in a known issue opened at 18:29 PT that evening on Microsoft Learn. This is the half of the update's personalization failure that had no vendor entry until then, after six days of user reports. The acknowledgment changes what is known, not what you can do: Microsoft published no workaround and no fix as of September 2, 2026.
- The new entry is titled "Desktop background settings are lost or reset on some devices", opened at 18:29 PT on September 2, 2026.
- Microsoft's mechanism: the issue prevents the correct loading of settings regardless of their value, and a default black background is used instead.
- Microsoft says other desktop settings may be affected too, naming slideshow settings and contrast themes.
- Affected platforms are Windows 11 25H2 and 24H2 only. The originating update is KB5120998, OS build 26100.9278, released August 27, 2026.
- No workaround appears under the entry, and no fix had shipped as of September 2, 2026.
Why resetting your wallpaper does not hold
The most useful line in the entry is the mechanism: the issue prevents the correct loading of settings, regardless of their value, and in this case a default black background is used instead. That is a load failure, not a value being overwritten. Your chosen wallpaper is most likely still recorded. Windows is not reading it.
That explains the reports of the reset recurring on restart even after the wallpaper was set again. Setting a value that is never read changes nothing, which is why the obvious remedy has been failing since the update shipped.
The update this traces to
KB5120998 is the August 27, 2026 preview update for Windows 11 25H2 and 24H2, OS builds 26200.9278 and 26100.9278, per Microsoft Support. It is a non-security preview, and it carries a repositionable taskbar, a smaller taskbar size option, selectable Start menu sizing, and administrator protection off by default.
One update, two known issues, both in the same place: settings that fail to load. That is the pattern to hold on to, because it predicts which repairs will not work.
| Known issue | Opened | State as of September 2, 2026 |
|---|---|---|
| Mouse customization is reset on non-English Windows devices | August 28, 2026, 15:36 PT | Acknowledged, no fix |
| Desktop background settings are lost or reset on some devices | September 2, 2026, 18:29 PT | Acknowledged, no fix |
What is still missing
No workaround appears under the new entry. Microsoft has published no registry change, no repair command and no supported way to get your background back while the update stays installed.
There is no fix date either. As of September 2, 2026 there is no build number, no KB and no published target for either of the two KB5120998 issues. What is known now is the mechanism and the affected versions. When it closes is not.
Two other things are unpublished and worth naming rather than guessing at: how many devices are affected, and whether removing the update restores a desktop that has already gone black. Microsoft's entry says only that manual restoration of the settings does not work. The next scheduled chance for a fix is the monthly security update, and Microsoft has not said this issue will be in it.
What you can do today
1. Confirm the update is there. Open Settings, then Windows Update, then Update history, and look for KB5120998. If the desktop went black without it, this entry is not your explanation.
2. Stop re-applying the wallpaper. Microsoft documents manual restoration as ineffective for this issue, and each attempt tells you nothing about the machine.
3. If a black desktop is worse than losing the preview features, remove the update: Settings, then Windows Update, then Update history, then Uninstall updates, select KB5120998, then restart. The cost is the four features listed above. It is not a security cost, because KB5120998 carries no security content.
4. If you are on 25H2 or 24H2 and have not installed KB5120998, do not install it while both issues are open. It is optional.
5. Watch the known issue entry rather than the headlines. The resolved date and the fixing build get recorded there first, and the entry now exists for both halves of this update.