Microsoft Teams and Outlook might fail to launch on ARM-based devices

What changed

After the August security update, Teams and the new Outlook could fail to start on new or freshly installed ARM-based Windows devices. The September cumulative updates contain the Windows fix.

Why it matters

Affected ARM devices could lose both primary communication clients, creating an immediate user-impact and support issue after provisioning or patching.

Known limitations

• Availability, prerequisites and rollout scope remain authoritative in the linked Microsoft documentation.

Now check

• Install KB5124008 on Windows 11 24H2/25H2 or KB5124012 on Windows 11 26H1
• Confirm Auto Super Resolution Package 1.0.19.0 or later on affected devices
• Launch Teams and the new Outlook on representative ARM devices after restart