Microsoft Windows 11 ARM update breaks Teams and New Outlook

Microsoft has acknowledged an issue where Microsoft Teams and the New Outlook for Windows fail to launch or crash immediately on ARM-based devices. The problem stems from security updates released on or after August 11, 2026, specifically involving update KB5121003.

The issue primarily affects modern Store-based applications on Windows 11 versions 24H2, 25H2, and 26H1, including hardware using Qualcomm Snapdragon X processors such as the Surface Pro 11 and Surface Laptop 7. Notably, classic Win32 applications like Word, Excel, and the classic version of Outlook remain unaffected.

As a workaround, Microsoft recommends that users install the Auto Super Resolution Package (version 1.0.19.0 or later) from the Microsoft Store. While this package is designed for AI-driven image enhancement in gaming on Copilot+ PCs, it serves to mitigate the application failures. A permanent fix is expected in a future Windows update.