

The calendar owner re-shares the calendar in Outlook on the web, Outlook on iOS, or Outlook on Android.The recipient removes the calendar that was previously shared to them.To manually upgrade a shared calendar to use the new approach, follow these steps: Over time, Outlook will automatically upgrade all shared calendars to use the new approach, including calendars shared with delegate permissions. If a calendar was shared with a view or edit permissions but using the old approach, you can now work around the error and manually upgrade the calendar sharing to use the new approach. You cannot use the calendar REST API to view or edit such calendars (or their events) if the calendars were shared using the old approach.You can use the calendar REST API to view or edit shared calendars only if the calendars were shared using the new approach.The new approach is currently available for sharing calendars with view or edit permissions, but not with delegate permissions.


The calendar owner should remove the user’s access to the calendar and then re-add the user’s access (the can edit permission is needed to schedule to a calendar via the integration). The owner of the calendar should right-click on the calendar to open the Sharing Permissions (for a shared mailbox, a user with access to manage the mailbox’s sharing permissions must open the shared mailbox directly). Note: This issue can't be fixed on the desktop application.
