Microsoft Teams, Outlook Crashes Following August 2026 Updates on ARM-Based Devices
Brief
Microsoft has confirmed a known issue causing Microsoft Teams and the new Outlook for Windows to crash or fail to launch on ARM-based PCs after installing security updates released on or after August 11, 2026.
The problem traces back to the KB5121003 update , part of Microsoft’s August 2026 Patch Tuesday rollout, and specifically affects devices running on Windows-on-ARM silicon, such as the Surface Pro 11 and Surface Laptop 7.
According to an advisory Microsoft posted to the Windows release health dashboard on September 1, 2026, at 19:20 PT, affected users may find that Teams and the new Outlook either refuse to open at all or close unexpectedly shortly after launching.