Tracked Windows update
KB5121003 known issues and fixes
August 2026 security update for Windows 11 24H2 and 25H2. Linked here to the ARM Teams/new Outlook launch issue.
- Release date
- Windows versions
- Windows 11 24H2, Windows 11 25H2
- OS builds
- 26200.9168, 26100.9168
- Official source
- KB5121003 — Microsoft Support
- Last verified
This is a directory of TraceCheck's tracked records, not a complete list of every vendor issue. Zero tracked records does not establish that an update is problem-free.
TraceCheck cross-reference
What role does this KB play?
Keep the update linked to the failure separate from the update linked to its resolution. These roles come from the cited issue records.
| Issue | This KB's role | Evidence |
|---|---|---|
| Teams / new Outlook fail to launch on ARM after KB5121003 | Originating update | Microsoft [1] · Microsoft [2] |
An originating update identifies the documented association; it does not establish the technical root cause. A resolving update applies to its listed Windows versions. This historical index does not identify today's latest update.
Known issues
No active issue records are currently tracked for this update.
Resolved issues
Resolved Resolution recorded 2026-09-08
Teams / new Outlook fail to launch on ARM after KB5121003
Microsoft confirmed launch failures or unexpected exits in Teams and the new Outlook on ARM devices after the August 2026 security update. New or freshly imaged PCs without Store updates are more likely to be affected. Windows 11 24H2/25H2 updates from KB5124008 onward resolve this documented issue.
Windows 11 26H1; Windows 11 25H2 · KB5121003; Windows 11 24H2 · KB5121003
Recorded update fix: Documented symptom resolution · Windows 11 24H2, Windows 11 25H2 · Check instructions
Compatibility reports
No separate unconfirmed compatibility reports are currently tracked.
Related fixes and workarounds
Install the applicable Windows update for ARM app launches
FACT Official fix · vendor fix
Microsoft records the resolution in KB5124008 and later Windows 11 24H2/25H2 updates. The linked package is historical, not necessarily the latest applicable update. This package scope excludes 26H1.
Documented symptom resolution
Applies to: Windows 11 24H2, Windows 11 25H2.
Risk: medium (TraceCheck editorial assessment, not a vendor success rate)
Store-package workaround for affected pre-September 8 devices
FACT Official workaround · workaround
For affected devices on a Windows update predating September 8, open Microsoft Store, select Downloads, check for updates, and install Auto Super Resolution Package version 1.0.19.0 or later. Microsoft says this workaround is unnecessary after the Windows resolution.
Documented symptom resolution
Applies to: Windows 11 24H2, Windows 11 25H2, Windows 11 26H1.
Risk: low (TraceCheck editorial assessment, not a vendor success rate)
Evidence
- KB5121003 — Microsoft Support
Microsoft · Vendor documentation
Supports: Release date, Windows 11 24H2/25H2 applicability and OS builds. This KB is a historical record, not a claim about the latest update.
Change history
No earlier verified state transitions are recorded.