Home windows 11’s August replace broke Groups and Outlook on Arm PCs

After putting in Home windows safety updates launched on or after August 11, 2026, (KB5121003), Microsoft Groups and the brand new Outlook for Home windows may fail to launch or may shut unexpectedly on Arm-based units, equivalent to Floor Professional 11 and Floor Laptop computer 7. Basic Outlook, Phrase, Excel, and different purposes will not be recognized to be affected. This difficulty is most probably to happen on new or freshly imaged PCs that haven’t but put in any Microsoft Retailer updates.

Microsoft says the difficulty impacts Home windows 11 variations 24H2, 25H2, and 26H1, and that the corporate is engaged on a repair that will probably be made accessible with a future Home windows replace.

For now, for those who’ve put in the KB5121003 replace and also you’re experiencing instability with Microsoft Groups and new Outlook, Microsoft’s supplied workaround is to open the Microsoft Retailer, choose Downloads → Test for updates, then set up the most recent replace for the Auto Tremendous Decision Bundle (model 1.0.19.0 or later).

This downside is only one extra in an extended line that traces again to the August Patch Tuesday replace. In latest weeks, customers have additionally reported that the replace breaks printers and PDFs on Home windows 11 and crashing video games and inflicting different PC instability points.