Update Teams mobile app by October or lose your calendar

Microsoft has shortened the deadline for updating the Teams mobile app to ensure users maintain access to their calendars. Originally set for late October, the updated deadline is the beginning of October, giving users until the end of September to upgrade their iOS and Android apps. The web and desktop versions remain unaffected.

Users with automatic updates enabled should receive a compatible version without manual intervention. Managed devices require administrators to deploy updated Teams apps. Microsoft has declared that older versions will lose calendar access, signaling the end of support for the Exchange Web Services (EWS) in Exchange Online, which will be disabled on October 1, 2026.

EWS has been in use since 2007 and was announced for retirement in 2023, with Microsoft citing the need to maintain a reliable calendar experience on iOS and Android devices and ensure compatibility with ongoing Teams service updates. Administrators can temporarily re-enable EWS in on-premises Exchange Server through policy settings, but the service will be permanently retired next year, with no exceptions granted past April 2027.