"After installing Windows security updates released on or after August 11, 2026, (KB5121003), Microsoft Teams and the new Outlook for Windows might fail to launch or might close unexpectedly on ARM-based devices, such as Surface Pro 11 and Surface Laptop 7," Microsoft explained in a Windows release health update.
Microsoft's Windows release health update
Microsoft confirmed last week that a known issue prevented Microsoft Teams and the new Outlook for Windows from starting on ARM-based Windows PCs after customers installed security updates released since the August 2026 Patch Tuesday. The company said the problem was observed on devices running Windows 11 24H2 or later that had not installed Microsoft Store updates.
KB5124012: the September Patch Tuesday fix
On the evening of the September 2026 Patch Tuesday, Microsoft released cumulative updates that addressed the problem. The company said the issue "was resolved by Windows updates released September 8, 2026 (KB5124012), and updates released after that date," and it recommended that users install the latest update for their devices because those updates "contain important improvements and issue resolutions, including this one."
This site is the portfolio.
OSINTSights runs on Cloudflare Workers, D1, R2, and Vectorize, with an AI pipeline on Hetzner ARM. Nubivance designed, built, and operates it. We do the same for clients.
See what we buildAffected devices and installations
Microsoft named ARM-based devices such as the Surface Pro 11 and Surface Laptop 7 as examples of machines where Teams and the new Outlook might fail to launch or close unexpectedly. The company noted that classic Outlook, Word, Excel, and other applications were not known to be affected. It added that the issue was most likely to occur on new or freshly imaged PCs that had not yet installed any Microsoft Store updates.
Temporary workaround: update the Auto Super Resolution Package
While Microsoft has not disclosed the root cause of the failures, it advised affected customers to update the Auto Super Resolution Package as a temporary workaround. Microsoft described that package as the component that enables "Copilot+ PCs to use AI to make gameplay smoother," and recommended the update while the official patch rollout completed.
August update cascade: related known issues
The Teams and Outlook launch failures were the latest in a string of problems Microsoft acknowledged after August updates. On August 24, Microsoft confirmed that August 2026 .NET Framework updates were breaking printing and PDF exporting in applications that use the Windows Presentation Foundation (WPF) UI framework. Days later, the company began rolling out a fix for a bug where peripherals with built-in RGB lighting triggered gaming issues and system crashes with "EXCEPTION_ACCESS_VIOLATION" errors on Windows 11 systems. Microsoft also told customers to ignore alerts that Microsoft Defender Antivirus had been turned off after installing updates released the previous month, and this week resolved known issues that wiped custom mouse settings and Windows desktop settings on some Windows 11 systems after installing the KB5120998 August 2026 preview update.
What this means for technologists, affected enterprises, and end users
- Technologists and security teams: Apply the September cumulative updates (including KB5124012) promptly to affected ARM-based Windows 11 24H2 or later devices and verify Microsoft Store updates are present on newly imaged systems.
- Affected enterprises and procurement leaders: Audit freshly imaged ARM device inventories (Surface Pro 11 and Surface Laptop 7 were cited examples) to confirm Microsoft Store packages and the Auto Super Resolution Package are updated before broad deployment.
- End users and IT help desks: If Teams or the new Outlook fail to launch after August updates, install the September cumulative update and, as an interim step if needed, update the Auto Super Resolution Package as advised by Microsoft.
Microsoft has fixed the immediate failure and asked customers to update devices; the company has not yet disclosed the root cause. Given the cluster of August and September update issues Microsoft enumerated, customers and administrators will likely be watching whether Microsoft provides a deeper explanation for the chain of regressions and how it will prevent similar disruptions after future Patch Tuesdays.
