When iCloud breaks your Outlook

Recently we saw an increasing number of tickets where user complained about issues retrieving Free/Busy data while scheduling a meeting or for shared calendar.

When trying to schedule a meeting you would see only hash marks

No F/B data in Scheduling Assistant


After installing iCloud users cannot retrieve Free/Busy data or content from shared calendar. On shared calendar user will see “no connection”

At the same time Outlook Connection Status shows an established connection (the procedure is explained here). Also a Fiddler trace and parsing the MapiHttp logs with Get-MAPIStats.ps1 shows connectivity and no server-side errors.


After some troubleshooting my co-worker figured out that lately iCloud was installed, which comes with an add-in for Outlook. The issue was resolved as soon as the add-in was disabled. But I wanted to know what exactly the issue is as others could use iCloud without issues.

One thing I realized was the formating after the installation

This reminded me checking my regional settings

My Windows 10 is English, but I’ve chosen German for formating. After I switched to “Match Windows display language (recommended)” everything started working.

The other solutions to fix F/B and shared calendar data access are:

  • disable the Outlook add-in (steps are described here)
  • uninstall iCloud


I’m wondering how something like this is possible these days. I wrote above Workaround and not Resolution on purpose as the only resolution can be done by the developers of iCloud. I hope this helps and you can save time with troubleshooting.


6 thoughts on “When iCloud breaks your Outlook

  1. Hi,

    that does not work with a German Windows 10 and German Office 2016 on prem and Office 365 Account.
    Does anybody has a clue to get the iCloud plugin up to speed?

    Thank you.


  2. I also dicovered that the iCloud plugin messes Outlook up. However I am no able to use the workaround above. English Win 10, Swedish regional settings (set to match win display language). Is there anyone that has found another solution?


  3. iCloud add in breaks my Outlook to the extent 40-60% of outbound mail won’t send until I disable the add-in. While some emails consistently won’t send with the add-in enabled, others are intermittent.


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