Outlook Unable to Open iCalendar after Windows 10 Anniversary Update 1607


After posting this fix I discovered that the process had removed any distribution lists (Group emails) that I had saved in Outlook. The contacts were there but the groups were gone. I would therefore recommend backing up any mail groups before the Anniversary Update occurs to prevent having to recreate them all – easiest way to do this is to copy the list to your local Outlook address book.



I know Microsoft hate Apple and vice versa but you’d think they’d fully test any Windows updates with the most popular applications before releasing them. Clearly not!

I’ve just suffered this annoying issue on my desktop. Following Windows Update moving my system to Windows 10 v1607 (known as the Anniversary edition), my iCloud calendar would no longer open in Outlook.

If this happens to you then the FIRST THING TO TRY (after an obligatory reboot) is to uninstall iCloud for Windows.

To do this:

  • Log out of iCloud
  • Open the Windows Control Panel
  • Open Programs
  • Uninstall iCloud for Windows
  • You will be prompted to reboot (if not do so)


  • Now download the latest version of icloud from https://support.apple.com/en-gb/HT204283
  • Reinstall iCloud for Windows ensuring Outlook is NOT open
  • Select the settings you want and login to iCloud when prompted


iCloud should now log back into the cloud and start to repopulate your calendar and tasks.

There is also another bug in Windows 10 1607 that impacts the synchornisation of Outlook and iCalendar. Details of this issue can be found on the Microsoft site at:


I would not implement this unless you are having problems after reinstalling.


Taff Lovesey
www.lovesey.net (fantasy novel author site)

About taffybach

Author of the young adult fantasy novel series, The Portal Chronicles, including The Spider Gem and The Shimmering Gate. When not writing and promoting Taff runs a small IT support company, LITES PC based in Bourne UK.
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