Microsoft has resolved a defect that blocked Teams and Outlook from launching on ARM-powered Windows machines following security patches distributed since mid-August 2026.

The software maker acknowledged the problem affected users running Windows 11 24H2 or later on ARM processors—including the Surface Pro 11 and Surface Laptop 7—who had not yet applied Microsoft Store updates.

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

According to Microsoft's statement, the launch failures were confined to these two applications. "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."

While the underlying cause remains undisclosed, Microsoft initially suggested updating the Auto Super Resolution Package—a component that leverages AI to enhance gaming performance on Copilot+ PCs—as a temporary solution.

Fixed by Patch Tuesday cumulative updates

Following the release of September 2026 Patch Tuesday cumulative updates, Microsoft announced the defect had been remedied in KB5124012 and urged users to install the latest patches.

This issue was resolved by Windows updates released September 8, 2026 (KB5124012), and updates released after that date

Microsoft

The company emphasized the importance of deploying the newest available updates, stating they contain critical enhancements and problem fixes.

This resolution represents the latest in a string of problems stemming from August's Windows update cycle. Microsoft confirmed on August 24 that .NET Framework patches from that month were causing printing and PDF export failures in applications built on the Windows Presentation Foundation (WPF) UI framework.

Shortly thereafter, the company began distributing patches for a separate issue triggered by peripherals featuring integrated RGB lighting, which caused gaming malfunctions and system crashes displaying EXCEPTION_ACCESS_VIOLATION errors on Windows 11.

Microsoft also instructed customers to disregard notifications indicating Microsoft Defender Antivirus had been disabled following last month's updates.

This week brought additional fixes for problems that erased personalized mouse configurations and Windows desktop settings on certain Windows 11 systems after installation of the KB5120998 August 2026 preview update.

Source: BleepingComputer