Apple Bug Causes Excessive Memory Consumption for Exchange Users Syncing with iOS 6.1-Based Devices

Apple Bug Causes Excessive Memory Consumption for Exchange Users Syncing with iOS 6.1-Based Devices


Recently, one of our clients noticed that their Microsoft Exchange 2010 server was chewing through free space on its hard disk at an alarming pace - and for no apparent reason. After some investigation, we were able to trace the issue to a bug with Apple's iOS 6.1 that has been affecting a number of Exchange users.

The bug is due to Apple code that syncs calendar events to a user's Exchange mailbox using ActiveSync. According to Apple support, the issue is triggered when a user on an iOS 6.1-based iPhone or iPad responds to an exception to a recurring calendar even through Microsoft Exchange 2010 SPI1 or later. When this occurs, users may notice an increased activity in CPU use, memory consumption, transaction logs and battery drain. The server may also block the iOS device as a result. Furthermore, there may be connection issues with Microsoft's Office 365 cloud service due to the bug.

Microsoft support has offered a few workarounds to avoid this issue:

  • Remove Microsoft Exchange from the iOS device
  • Use URL Rewrite to block specific clients from Exchange
  • Block all iOS 6.1 and 6.1.1 users

Apple's resolution is to update to iOS 6.1.2.

Because this bug is causing major IT headaches in the form of slow email downloads, duplicate calendar items, and restricted administration of calendar items, a number of enterprise users have been told by their IT staff to refrain from using iOS 6.1 devices with corporate servers. Reports vary as to exactly how widespread this issue is, but ars technica reports that business of all sizes are actively limiting, or - in some cases - blocking iOS devices all together.

If you have noticed any of the symptoms affecting your organization's Microsoft Exchange 2010 server, contact your IT support immediately to have the issue resolved. For more up to date information, visit Microsoft support.

Until next time-

Charlie Nadler
Switchfast Technologies
IT Consulting and Managed Services