Update Teams mobile app by October or lose your calendar
Microsoft has moved forward the deadline for Teams mobile users to update the app, warning that older iOS and Android versions will lose calendar access from October 2026. The change is linked to the retirement of Exchange Web Services in Exchange Online, and matters particularly for organisations managing app updates centrally.
Users have until the end of September to install a compatible version, while desktop and web Teams are unaffected. Automatic updates should handle most personal devices, but administrators must deploy updates to managed phones; Microsoft will disable Exchange Online EWS on 1 October 2026, with no exceptions after April 2027.
In short
- Update Teams mobile by September to retain calendar access.
- Only iOS and Android Teams apps are affected.
- The change follows Exchange Web Services retirement.
Explained simply
Teams is Microsoft’s app for workplace chat, meetings and calendars. It can connect to Exchange Online, Microsoft’s hosted email and calendar service, which some older versions of the mobile app use to retrieve calendar information.
Microsoft is retiring Exchange Web Services, a system that lets apps access Exchange Online data. Organisations that manage staff phones centrally may need to install a compatible Teams update themselves; the change concerns mobile calendar access, while Teams on desktop and the web is unaffected.