Exchange 2013 Hybrid Calendar Availability not working after Calendar sharing request RRS feed

  • Question

  • Hello Tech Net,

    I am having an interesting problem that hopefully someone might have some insight on or at least help me get going in the right direction. First here is a breakdown of my setup, I have an on premise Exchange 2013 setup currently patched to CU 15. There is a Citrix load balancer setup in front of my Client Access servers to provide pre-authentication since we currently have a requirement for that. My Exchange is setup in a hybrid to Office 365.

    Further to that, because we are doing pre-authentication it means by default Calendar Availability to Office 365 for my on premise Exchange did not initially work. I had to get around that by setting the TargetSharingEpr property in my Organization Relationship in Office 365 which points to a different url which connects through the same load balancer to my Client Access servers that has no pre-authentication setup. This  does allow Calendar availability from Office 365 to my on premise Exchange to work.

    Where my problem comes in is recently an on premise user sent a Calendar Sharing request to an Office 365 hybrid user. After the Hybrid user accepted the request, he can no longer see the availability of the on premise users Calendar at all. His Outlook and OWA in Office 365 both say “could not be updated” when viewing the Calendar of the on premise user. I was able to replicate this problem with a test account so I know this Calendar sharing request is the source of the problem. As any other Office 365 Hybrid user can view the Calendar of the on premise user without a problem.

    I already opened a support ticket with Microsoft who have already given up on the issue with no resolution. The most they could say is likely the Calendar sharing request has some information pertaining to my on premise Exchange that is overriding the default Organization Relationship setup and sending the connection for this Office 365 user through to the load balancer setup that has pre-authentication. The only thing I can think of doing is trying to dig through the users mailbox using MFCMAPI to try and pin point where the Calendar settings might be stored in the mailbox. But it’s not like there is a manual on where these settings are stored when using MFCMAPI to view the mailbox.

    If anyone out there has a thought or advise, it is more than welcome as I am stumped as to what to do right now.

    Tuesday, April 11, 2017 7:37 PM

All replies

  • I suggest you bypass the load balancer and SSL offloading by establishing a direct network connection between Office 365 and your Exchange server, and that means a new IP address, firewall, NAT, and probably another name added to your SSL certificate.  But by doing that you can make sure there's nothing between Office 365 and your on-premises server that's not supported.

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    • Proposed as answer by Jason.Chao Wednesday, April 12, 2017 8:24 AM
    Tuesday, April 11, 2017 11:32 PM
  • Hi Nicholas,

    Please use Microsoft Remote connectivity Analyzer tool and test free busy Information for Both cases and share results. Lets have a look what is the difference before calendar sharing scenario and after calendar sharing scenario.



    Wednesday, April 12, 2017 7:41 AM
  • Hello Vbhadauria,

    I guess I should have said in my initial post. I already ran the Microsoft Remote connectivity Analyzer which reports no issues with free busy what so ever. Even when testing with the Office 365 hybrid user who can't see the calendar for the one on premise Exchange 2013 user.


    Thursday, April 13, 2017 7:38 PM