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Windows

My desktop wallpaper turned black after the August Windows update

After the optional preview update KB5120998, released August 27, 2026, some Windows 11 PCs show a solid black desktop background. Slideshow settings and contrast themes can be lost too, and setting the wallpaper again by hand does not stick. Microsoft confirmed the issue and fixed it in the September 8, 2026 updates.

Affects

Versions

  • Windows 11, version 24H2
  • Windows 11, version 25H2

Builds and updates

  • KB5120998
  • OS Build 26100.9278
  • Build 26200.9278

What you see

  • The desktop background is a solid black color after a restart
  • Choosing a picture again in Personalization does not hold
  • Other desktop settings are lost as well, such as "slideshow settings or contrast themes"
  • The problem starts after the August 27, 2026 preview update

Why it happens

Confirmed Following installation of Windows updates released August 27 2026 (KB5120998), "some Windows Desktop settings fail to load", which leaves "desktop backgrounds displaying as a solid black color". Microsoft says that "attempting to manually restore customized settings does not work", because the settings fail to load whatever their value. [1] [2]

Likely The change that breaks personalization reaches PCs in stages, so two PCs on the same update do not always behave the same way. [4]

When it shows up

A home or unmanaged PC that can install the September 8, 2026 security update

You are in this case if:

  • Update history lists KB5120998, installed on or after August 27, 2026
  • The background is black and Personalization will not hold a new picture
  • Settings > Windows Update offers an update released September 8, 2026 or later

1 fix below

A PC that cannot take the September update yet, for example one whose updates an IT department approves

You are in this case if:

  • Update history lists KB5120998 and nothing released September 8, 2026 or later
  • Settings > Windows Update shows no newer update, or says updates are managed by your organization

2 fixes below

The steps that killed it

The steps are behind a quick check

There are two ways in and both take a few seconds. Signing in opens the steps on every bug page; so does reading the picture.

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Drawing a picture for you.

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Keeping it away

  • Leave optional preview updates alone unless you need something in them. BleepingComputer notes that a preview update installs automatically only if "Get the latest updates as soon as they're available" is turned on.
  • Check the Windows release health page for your Windows version before installing a preview update.

Sources

  1. Windows 11, version 24H2 known issues and notifications
    Microsoft Learn, 2026-09-12
  2. Microsoft says KB5120998 Windows update resets desktop settings
    BleepingComputer, 2026-09-03
  3. Microsoft fixes bug that wiped Windows desktop settings
    BleepingComputer, 2026-09-10
  4. Microsoft keeps breaking Windows 11's most basic features, now trashing wallpapers after cursors
    Windows Latest, 2026-09-04
  5. 5 Ways to uninstall an update manually on Windows 11
    Pureinfotech, 2026-03-17
  6. Change the desktop background in Windows
    Microsoft Support

First seen 2026-09-02 · Vendor status fixed · Fixed in KB5124008, released September 8, 2026 · Last verified 2026-09-14