"Free/Busy information couldn’t be retrieved because the attendee's Mailbox server is busy" error in a hybrid deployment or a cross-premises environment
However, you experience issues when you try to use the organization relationship. For example, free/busy lookups don't work. When a user tries to look up free/busy information about another user, the user receives an error message that resembles the following:
- You use the TargetSharingEPR parameter of the organization relationship to specify the EWS endpoint.
- The version of Exchange is different in the two organizations. For example, one organization is running Exchange Server 2010 and the other organization is running Exchange Server 2016 or Exchange Server 2013.
If you're running Exchange Server 2010 in the on-premises environment, the versions of Exchange in Office 365 and in your on-premises environment are different. This combination, together with the misconfiguration of having the TargetSharingEPR parameter set, causes this issue.
To set the TargetSharingEPR parameter to Null, follow these steps:
- Take one of the following actions:
- In a hybrid deployment, connect to Exchange Online by using remote PowerShell. For more information, go to Connect to Exchange Online using remote PowerShell.
- In a cross-premises scenario, open Exchange Management Shell. For more information, go to Open the Exchange Management Shell.
- Check whether the value of the TargetSharingEPR parameter is blank. To do this, run the following command:
- If the value of the TargetSharingEPR parameter isn't blank, run the following command:
set-OrganizationRelationship <name of organization relationship> –targetSharingEPR $Null
- Make sure that Autodiscover URLS can be resolved internally and externally for the organization with which you want to share free/busy information.
- Make sure that the organization with which you are sharing free/busy information has its external EWS endpoint set up.
Article ID: 2838688 - Last Review: 04/25/2016 11:13:00 - Revision: 9.0
- o365e o365m o365022013 o365 o365a hybrid KB2838688