Update Teams mobile app by October or lose your calendar
- ID
- 9655
- Status
- summarized
- Published
- 31 Jul 2026, 10:30 PM
- Fetched
- 31 Jul 2026, 10:54 PM
- Provider
- The Register
- Category
- technology
- Original URL
- https://www.theregister.com/software/2026/07/31/update-teams-mobile-app-by-october-or-lose-your-calendar/5281773
- Source URL
- https://www.theregister.com/headlines.atom
Summary
- Score
- 6.0
- Created
- 31 Jul 2026, 10:55 PM
- Tags
- Audience
- developerssaas_startup_founders
What happened
Microsoft has moved the deadline for updating Teams mobile apps (iOS and Android) from late October to end of September 2026, after which older versions lose calendar access. This is tied to the disabling of Exchange Web Services (EWS) in Exchange Online on October 1, 2026—a protocol dating to 2007 that stopped receiving features in 2018 and was flagged for retirement in 2023. On-premises Exchange Server EWS is unaffected, and admins can temporarily re-enable EWS via policy until a hard cutoff in April 2027.
Why it matters
If your organisation runs Microsoft 365 with managed mobile devices, you must push an updated Teams app before October 1, 2026 or users on iOS/Android lose calendar access. If you have integrations built on EWS against Exchange Online, plan migration now—temporary re-enablement via policy only buys time until April 2027, with no exceptions after.
Discussion angle
For any builders maintaining EWS-based integrations with Exchange Online, what are the realistic migration paths (Graph API?) and what breaks if you miss the October 1 cutoff versus the April 2027 hard stop?