Microsoft Addresses Teams and Outlook Crashes on ARM-Based Windows Devices

REDMOND, Wash. — Microsoft is deploying emergency fixes to resolve widespread application crashes and launch failures affecting Microsoft Teams and the New Outlook client on ARM-based Windows PCs following a recent software update.

The technical disruption impacts users of Windows devices powered by ARM architecture, including the Surface Laptop 7 and Surface Pro 11. The issues emerged shortly after the rollout of cumulative updates released during the August 2026 Patch Tuesday cycle. Specifically, update KB5121003 has been identified as the trigger for the instability, causing the communication and email applications to fail upon startup or crash unexpectedly during use.

Microsoft acknowledged the problem on Wednesday, stating that the company is actively working to address the failures. The tech giant confirmed that a patch is being developed and distributed to restore full functionality to affected systems. While the update KB5121003 was intended to deliver security enhancements and system improvements, it inadvertently introduced compatibility conflicts within the ARM ecosystem for these specific applications.

Users have reported that the New Outlook client fails to open entirely, displaying error messages before closing. Similarly, Microsoft Teams users experienced intermittent disconnections and application terminations, disrupting video conferencing and chat capabilities essential for enterprise workflows. The outage has drawn attention from IT administrators managing fleets of ARM-based devices, who are currently advised to hold off on further updates until the remediation is complete.

Microsoft has not disclosed the specific root cause of the conflict between the update and the ARM architecture. The company declined to comment on whether the issue stems from a coding error in the update or a deeper incompatibility with the underlying operating system components on ARM chips. As the industry increasingly shifts toward energy-efficient ARM processors for laptops, such stability issues highlight the complexities of maintaining software compatibility across diverse hardware architectures.

The resolution timeline remains fluid as Microsoft tests and deploys the corrective patch. While some users have reported that rolling back the update temporarily restores service, this is not considered a long-term solution due to the security risks associated with running unpatched systems. IT professionals are monitoring official channels for guidance on when the fix will be universally available.

As of Wednesday morning, Microsoft has not provided an estimated time for the full resolution of the issue. The company continues to investigate the scope of the impact and is prioritizing the release of a stable update to prevent further disruption to global users relying on these core productivity tools.