Outlook Scheduling Assistant between Exchange 2010 and Exchange 2016 can not be contacted

Wendell Jones 21 Reputation points


I am migrating Onsite Exchange 2010 server mailboxes to Onsite Exchange 2016 server mailboxes. Everything SEEMS to work fine. I have moved about 10 mailboxes with no issue. The email clients automatically associate the mailbox to the correct exchange server without manual assistance. I have noticed the following behavior. I can send and receive external as well as internal email messages. I can also send and receive calendar invites between the two servers. The calendar events are updated correctly when accepted, rejected or when scheduling a new time. I can even write appointments directly to calendars between both servers.

The issue occurs when trying to use scheduling Assistant. I receive the following:

No Information. No Free/Busy information could be retrieved.
The recipient's server could not be contacted. Contact Administrator.

I have rebooted the exchange 2016 server and it did not correct the problem. I have tried using OWA as well as Outlook client with the same results.

Any assistance would be greatly appreciated.

Thank you very much.

Wendell Jones

Exchange Server Management
Exchange Server Management
Exchange Server: A family of Microsoft client/server messaging and collaboration software.Management: The act or process of organizing, handling, directing or controlling something.
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  1. Aholic Liang-MSFT 13,731 Reputation points Microsoft Vendor

    Hi @Wendell Jones ,

    The possible cause is that after the mailbox move is complete, the Exchange Server 2016 continues to proxy the EWS request to Exchange Server 2010 .
    Please refer to the resolution in the following link to restart the Autodiscover Application Pool and the Exchange Web Services Application Pool and see if it works.

    Can't see Free/Busy info after a mailbox moves to Exchange 2013 or 2016 - Exchange | Microsoft Learn

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