Since the 365 re-licensing, the calendar is no longer synchronized with my iphone

Ray Justin 20 Reputation points
2026-11-11T14:48:15.3466667+00:00

I've been using Apple Calendar on the iPhone for years and Outlook on the PC, until the last license renewal everything worked without any problems. Now nothing works anymore.

Outlook | Windows | Classic Outlook for Windows | For business
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  1. Hin Vo 1,755 Reputation points Independent Advisor
    2026-11-11T15:06:02.4633333+00:00

    Hi @Ray Justin

    To ensure I fully understand your situation and provide the most effective assistance, I’ll need a few additional details, such as:

    May I know how the account is configured on your iPhone? For example, is it added as a Microsoft Exchange account, through the Outlook app, or using another method?

    On your iPhone, is only the Calendar affected, or are Email and Contacts also not synchronizing?

    Have you tried removing and re-adding the Microsoft 365 account on the iPhone yet? If so, did you receive any error messages during the setup process?

    Any update would be appreciated.

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  2. AI answer

    2026-11-11T14:48:28.16+00:00

    For iPhone calendar sync, the key issue is usually the account type and sync relationship, not the Microsoft 365 license itself.

    1. On the iPhone, check how the account is added:
      • Go to Settings > Apps > Mail > Mail Accounts.
      • Select the account used for Outlook/Microsoft 365.
      • Make sure Calendars and Contacts are enabled.
    2. If there is no Calendars option, the account was likely added as IMAP.
      • IMAP and POP can sync email only and cannot sync calendar or contacts.
      • Delete the account from the iPhone and add it again as Exchange for a Microsoft 365/Exchange account.
    3. If the account is already using Exchange ActiveSync but calendar items are still missing, re-create the mobile sync relationship:
      • Remove the account from the mobile device.
      • Sign in to Outlook Web App.
      • Go to Settings > Options > Phone > Mobile Phones or Mobile Devices.
      • Select the device’s ActiveSync relationship and choose Delete.
      • Restart the iPhone.
      • Add the account back on the iPhone and test calendar sync again.
    4. If Outlook add-ins on the PC create or modify calendar items, temporarily disable them, especially conference-room or meeting-related add-ins, then test again.
    5. If the calendar being viewed on the iPhone is Apple Calendar, confirm the events are being saved to the Microsoft 365/Exchange calendar and not to a local iPhone calendar or another account.

    Important points:

    • IMAP/POP will not restore calendar sync.
    • For Microsoft 365 business mailboxes on iPhone, the account should be added as Exchange.
    • A corrupted ActiveSync relationship can cause calendar items to stop syncing in either direction.
    AI-generated content may be incorrect. Read our transparency notes for more information.

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