Teams mobile calendar access will require an app update by October
Microsoft says older Teams apps on iOS and Android will lose calendar access unless users update by the end of September.
By Dominic Okoye · Staff Writer
· 3 min read
Microsoft has moved up the deadline for preserving Teams mobile calendar access, telling iOS and Android users to update the app by the end of September. Older mobile versions will lose access to the calendar after the new deadline, a change that puts pressure on IT teams managing corporate devices.
The change applies only to the Teams apps for iOS and Android. Microsoft’s web and desktop Teams clients are not affected, according to the company’s notice.
Microsoft had previously pointed users to a late-October cutoff. The company has now shifted the effective deadline to the start of October, giving users less time to move to a supported mobile version.
Why will Teams mobile lose calendar access?
Microsoft said older Teams mobile apps will lose calendar access because the company is keeping the mobile calendar experience aligned with current Teams service updates. The timing also intersects with Microsoft’s broader retirement of Exchange Web Services, the older Exchange interface used by applications to reach mailbox and calendar data.
For individual users, the fix may be routine. Devices with automatic app updates enabled are likely to receive a compatible Teams version without manual action. The risk is higher in managed environments where IT administrators control app deployment, testing and release schedules.
Microsoft’s message to holdouts was direct: “Older versions will lose calendar access.” The company also said the change is meant to “maintain a reliable calendar experience on iOS and Android devices” and keep the apps compatible with Teams service updates.
What administrators need to check
Administrators responsible for mobile fleets will need to confirm that supported Teams versions are deployed before the end of September. That includes organizations using mobile device management or app management tools that can delay updates for testing, compliance or internal approval.
The company did not provide a workaround for older Teams mobile builds beyond updating the app. It also did not say that calendar access would be affected in Teams for desktop or web.
The deadline is part of a larger cleanup of Exchange Web Services in Exchange Online. EWS dates back to 2007 and has long been used by software vendors and internal integrations to connect with Exchange mailbox data. Microsoft stopped adding features to EWS in 2018 and announced its retirement in 2023.
Microsoft is scheduled to begin disabling EWS in Exchange Online on October 1, 2026. The on-premises version in Exchange Server is not covered by that shutdown, but Exchange Online customers are being pushed off the older interface.
Administrators will be able to temporarily re-enable EWS through a policy setting during the shutdown period. Microsoft has said that option will not last indefinitely, stating there will be “no exceptions past April 2027.”
EWS has also been abused in security incidents, including activity attributed to Midnight Blizzard. That history gives Microsoft another reason to retire the older access path, beyond normal product lifecycle management.
This story draws on original reporting from The Register.
