If you've noticed missing calendar appointments (e.g., lost meetings, delegate issues), or meeting updates from someone other than the original organizer, you're not alone. This issue has been reported in organizations with Microsoft Exchange, Outlook (2010, 2013 or 2016), Apple iPhones/iPads, Active Sync devices, Apple Macs running Outlook 2011 or 2016, and RIM Blackberries.  For more information see: Exchange Outlook Calendaring Problems

Exchange itself is usually not the root of the problem, the mail clients (ActiveSync, iOS devices, Blackberries, iCal) and their connectivity protocol tend to be the culprits.  Another cause of the issue is sync timing.  For instance, if someone accepts a meeting at 9am on an iPhone and a delegate declines it at 9:10am on a PC, but the iPhone is out of signal range and doesn't sync the meeting until say 9:30am., what happens to the meeting? 

There is no simple solution, but the following tips may lessen the frequency of calendaring issues:

  1. Run the same version of Outlook on all of your computers, at work and at home.  Mailbox owners and any delegates should be using the same version of Outlook with the latest service pack and updates on all computers that are used for calendaring. If you are in a mixed environment of Windows, Mac or mobile devices, each platform should use the same version and each device should have the latest service pack and updates.
  2. Only one person should process meeting requests. Other people, computers or devices that receive the meeting request should ignore them, i.e. leave them be, do not delete them do not process them.  Have no more than two delegates. 
  3. Manage your calendar exclusively from Outlook or OWA. Don't accept, decline, modify or invite others to appointments from your mobile device.  You can, however, create new appointments on your mobile device, (e.g., add one while checking out at a doctor's office).
  4. Make sure your mobile device has the latest OS/iOS version.  Often new devices do not, so be sure to check for updates, and do so BEFORE adding your Office365 account to the device.
  5. To change an entire series of meetings, cancel the original meeting and create a new one.  To change one instance, cancel just that meeting and create a new one to replace it.  Always put an end date on a recurring meeting.
  6. A "corrupt" meeting will remain that way until you delete it.  If it is a recurring appointment, delete all occurrences and reschedule it.
  7. When scheduling a recurring meeting, Microsoft recommends setting the end date no more than 6 months.  If you need to schedule a meeting for a longer period, start a new recurring meeting.

 For more information please see Outlook Troubleshooting Tools and  Best Practices for Office 365 Calendar users.

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Last updated: 
September 12, 2017