Summary: In my Windows 11 25H2 lab, the entire system tray disappeared after installing KB5121003 and disappeared again after installing the later KB5120998 cumulative preview. Removing KB5121003 rolled the VM back to OS Build 26200.8037 and immediately restored the clock, network, volume and notification area. This post documents the reproduction, rollback, temporary block and the follow-up test with KB5120998.
This is a lab reproduction, not a claim that every Windows 11 25H2 device will experience the same problem. At the time of writing, Microsoft does not list this exact whole-system-tray symptom as a known issue for KB5121003.
Lab environment and starting point
The test system was a non-touch Windows 11 25H2 virtual machine. The affected starting build was 26200.9168. Microsoft documents that build as the Windows 11 25H2 build delivered by the August 11, 2026 security update KB5121003.
Windows Update history also showed KB5121003 as successfully installed.
If you want to verify the installed state from PowerShell, use:
Get-HotFix -Id KB5121003What the problem looked like
After the update and restart, the taskbar itself still loaded, but the entire system tray area on the right side disappeared. The clock, network, volume and other notification-area icons were all missing.
The useful result came from comparing the same VM before and after removing the cumulative update.
Rollback test: remove KB5121003
One complication was Windows Update automatically offering the same security update again. To keep the first restart clean enough to test the rollback, I temporarily paused Windows Update before uninstalling KB5121003.
I then started the uninstall from an elevated PowerShell window. The command opens Windows Update Standalone Installer and asks for confirmation.
wusa /uninstall /kb:5121003After the removal completed, Windows required a restart to finish the servicing operation.
Result after uninstall: the system tray returned
The first restart after removing KB5121003 produced the clearest A/B result in the test: the system tray returned immediately. The clock, network, volume and the rest of the notification area were visible again.
The update was no longer installed after the rollback. Get-HotFix -Id KB5121003 returned no matching hotfix, and winver showed that the rollback returned Windows 11 25H2 to OS Build 26200.8037.
Prevent KB5121003 from reinstalling automatically
Because Windows Update can offer KB5121003 again, I used the PSWindowsUpdate module to hide the update after the rollback. PSWindowsUpdate is a third-party PowerShell module available from the PowerShell Gallery.
If the module is not already installed, install it from an elevated PowerShell session:
Install-Module PSWindowsUpdate -ForceAfter the rollback, resume Windows Update so the update becomes visible to the Windows Update API. Once KB5121003 is offered again, hide it before allowing another restart:
Hide-WindowsUpdate -KBArticleID KB5121003 -Confirm:$false
Get-WindowsUpdate -IsHidden -KBArticleID KB5121003
The H flag in the output confirms that KB5121003 is hidden. This was useful for keeping the VM on the working rollback build while I continued testing.
Then I tested the newer KB5120998 Preview
Leaving an August security cumulative update removed is not a good long-term answer, so I tested the later KB5120998 cumulative preview. Microsoft describes KB5120998 as a cumulative preview for Windows 11 25H2/24H2 and documents OS Build 26200.9278. Windows client updates are cumulative, so the later package also carries forward fixes from previous cumulative updates.
The release notes made this test particularly interesting: under Taskbar, Microsoft states that KB5120998 improves the reliability of loading the system tray area on non-touch PCs. My lab VM is a non-touch Windows 11 client, so this newer build looked like the better path to test. Microsoft lists this Taskbar change under the gradual-rollout section, so availability can vary by device even when KB5120998 is installed. In this VM, simply moving to build 26200.9278 did not restore the tray.
However, after installing KB5120998 and restarting, the entire system tray disappeared again.
So in this lab, KB5120998 did not provide a working replacement for the rollback. The issue was reproducible on both 26200.9168 with KB5121003 and 26200.9278 with KB5120998.
Test results
| Test state | OS build | Result |
|---|---|---|
| KB5121003 installed | 26200.9168 | System tray missing |
| KB5121003 removed | 26200.8037 | System tray restored |
| KB5120998 Preview installed | 26200.9278 | System tray missing again |
Hiding KB5121003 with PSWindowsUpdate allowed me to keep the working rollback state long enough to continue the lab tests.
Temporary lab workaround at a glance
- Pause Windows Update before uninstalling KB5121003.
- Run
wusa /uninstall /kb:5121003from an elevated PowerShell window. - Restart Windows and verify that the system tray returns.
- Install PSWindowsUpdate if it is not already present.
- Resume Windows Update so KB5121003 becomes visible again, then hide it before another restart.
- Verify the hidden state with
Get-WindowsUpdate -IsHidden -KBArticleID KB5121003.
Security warning: treat the rollback only as a temporary workaround
KB5121003 is a security update. Removing it rolls back the security fixes delivered by that cumulative update. Hiding it indefinitely would therefore leave the device below the current security servicing level.
KB5120998 is cumulative and carries forward previously released fixes, which is why I tested it as a possible safer path. Unfortunately, the system-tray problem returned on that build in my lab. For production systems, I would treat the rollback-and-hide method only as a short troubleshooting workaround while evaluating the security impact and waiting for a newer cumulative update or a Microsoft-supported resolution.
What this test proves — and what it does not
The controlled rollback gives strong evidence that the behavior on this VM is tied to changes present in the August cumulative update branch: the tray was missing on 26200.9168, returned on 26200.8037, and disappeared again on the later 26200.9278 cumulative preview.
It does not prove that KB5121003 or KB5120998 will cause the same symptom on every Windows 11 25H2 device, and it does not identify the exact component or code change responsible. The reproducible build transition is the useful troubleshooting result.
References
- August 11, 2026—KB5121003 (OS Builds 26200.9168 and 26100.9168) – Microsoft Support
- August 27, 2026—KB5120998 (OS Builds 26200.9278 and 26100.9278) Preview – Microsoft Support
Cloud and infrastructure professional with nearly two decades of experience in enterprise IT environments, spanning public cloud, private cloud, and hybrid architectures.