Note The Hybrid Configuration wizard that's included in the Exchange Management Console in Microsoft Exchange Server 2010 is no longer supported. Therefore, you should no longer use the old Hybrid Configuration wizard. Instead, use the Office 365 Hybrid Configuration wizard that's available at http://aka.ms/HybridWizard. For more information, see Office 365 Hybrid Configuration wizard for Exchange 2010.
Assume that you have a hybrid deployment of on-premises Exchange Server and Exchange Online, and you set up OAuth authentication by following the steps at Configure OAuth authentication between Exchange and Exchange Online organizations. In this situation, free/busy lookups between on-premises Exchange users and Exchange Online users no longer work. Users see hash marks ("\\\\") instead of free/busy information. However, free/busy lookups between on-premises Exchange users still work.
This issue may occur if the following conditions are true:
- Your on-premises environment contains both Exchange 2010 servers and Exchange 2013 servers.
- OAuth authentication is enabled.
Disable IntraOrganizationConnector functionality to prevent OAuth authentication for Autodiscover requests between on-premises Exchange Server and Exchange Online. To do this, follow these steps:
- Test OAuth authentication in your environment:
- Connect to Exchange Online by using remote PowerShell. For more info about how to do this, see Connect to Exchange Online using Remote PowerShell.
- Run the following command:
Test-OAuthConnectivity -Service EWS -TargetUri <external hostname authority of your on-premises Exchange deployment> -Mailbox <Exchange Online mailbox> -Verbose | fl
- If the test fails, this confirms that OAuth is not set up correctly. Go to step 2.
- Disable IntraOrganizationConnector. To do this, run the following command:
Set-IntraOrganizationConnector <connector_name> -Enabled $false
In addition to the symptoms that are described in the "Problem" section, if you examine the free/busy request in the Internet Information Services (IIS) logs, you see a "401" response that resembles the following:
Still need help? Go to Microsoft Community or the Exchange TechNet Forums.
2014-06-17 19:09:07 W3SVC1 Server 192.168.216.90
443 - 10.0.0.0 HTTP/1.1 ASAutoDiscover/CrossForest/EmailDomain//15.00.0959.014 -
hybrid.contoso.com 401 0 0 359
Article ID: 3001281 - Last Review: Dec 29, 2016 - Revision: 1