Resolve free/busy sharing issues in a hybrid Exchange environment

• Applies to:

  Exchange Server 2019, Exchange Server 2016, Exchange Server 2013, Exchange Online

Free/busy sharing and MailTips issues

After you set up a hybrid Microsoft Exchange environment, the following issues might occur:

• When a user who has an on-premises mailbox tries to use the Scheduling Assistant in Microsoft Outlook to retrieve free/busy information for another user who has an Exchange Online mailbox, free/busy sharing either doesn't work or works intermittently.

• When a user who has an on-premises mailbox tries to add the shared calendar of a user who has an Exchange Online mailbox, Outlook displays a "Could not update" message.

• When a user who has an on-premises mailbox drafts a message to a user who has an Exchange Online mailbox, MailTips aren't displayed. This issue can occur in Outlook or Outlook on the web.

Federation trust and authorization errors

When you try to configure the components that are required for free/busy sharing by using Hybrid Configuration wizard (HCW) or the Exchange Management Shell (EMS), you might encounter any of the following errors.

Errors when creating a federation trust

PowerShell failed to invoke 'Set-FederatedOrganizationIdentifier': An error occurred while attempting to provision Exchange to the Partner STS. Detailed Information "An error occurred accessing Windows Live. Detailed information: "The underlying connection was closed: An unexpected error occurred on a receive."."

PowerShell failed to invoke 'Set-FederatedOrganizationIdentifier': An error occurred while attempting to provision Exchange to the Partner STS. Detailed Information "An error occurred accessing Windows Live. Detailed information: "The underlying connection was closed: An unexpected error occurred on a send."."

HCW logs these errors in the HCW log file. If you use EMS, you encounter these errors when you run the Set-FederatedOrganizationIdentifier cmdlet.

Errors when adding a domain to a federation trust

PowerShell failed to invoke 'Add-FederatedDomain': Unable to reserve the URI "contoso.com" for the domain "contoso.com" on application identifier <application ID>. Detailed information: "An error occurred accessing Windows Live. Detailed information: "The underlying connection was closed: An unexpected error occurred on a send."."

HCW logs this error in the HCW log file. If you use EMS, you encounter this error when you run the Add-FederatedDomain cmdlet.

Error when creating authorization server objects

New-AuthServer -Name "WindowsAzureACS" -AuthMetadataUrl "https://accounts.accesscontrol.windows.net/contoso.com/metadata/json/1" Cannot acquire auth metadata document from 'https://accounts.accesscontrol.windows.net/contoso.com/metadata/json/1'. Error: The underlying connection was closed: An unexpected error occurred on a receive.

HCW logs this error in the HCW log file. If you use EMS, you encounter this error when you run the New-AuthServer cmdlet in EMS.

Error when testing OAuth connectivity

System.Net.WebException: The underlying connection was closed: An unexpected error occurred on a send. System.IO.IOException: Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host.

HCW logs this error in the HCW log file. If you use EMS, you encounter this error when you run the Test-OAuthConnectivity cmdlet.

Resolution

Any of the listed issues and errors can occur if TLS 1.2 isn't fully enabled and configured on all Exchange-based servers in your organization. Follow the guidelines in Exchange Server TLS configuration best practices to make sure that all the servers in your environment are compliant.

More information

• To diagnose free/busy issues in Outlook and Outlook on the web, see Demystifying hybrid free/busy and Free/busy sharing fails if TLS 1.2 is misconfigured.

• To check the TLS configuration in Exchange Server, use the Exchange Server Health Checker.

• To check a server's SSL/TLS configuration, use the Microsoft SSL Server Test or Qualys SSL Server Test.

• To check the TLS version of network traffic for a specific issue, trigger the issue while you use a network protocol analyzer to capture the network traffic. The following screenshot shows the TLS version of a ClientHello handshake that was captured by using Wireshark.

  

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