A Windows update released one month ago is still causing issues for some users, with reports of Microsoft Teams and Outlook closing unexpectedly or failing to launch outright. The KB5121003 Windows 11 update appears to be effecting Arm-based computers, such as some Surface models, exclusively.
In a Windows health update, Microsoft reports:
“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. Classic Outlook, Word, Excel, and other applications are not known to be affected. This issue is most likely to occur on new or freshly imaged PCs that have not yet installed any Microsoft Store updates.”
The issue is so far known to affect versions 24H2, 25H2, and 26H1 of the operating system. Microsoft says that it is currently working on a solution to the issue that will rollout in a future Windows update.
