Free/Busy lookups stop working for users in a cross-premises environment, or in a hybrid deployment of on-premises Exchange Server and Exchange Online. Additionally, these issues may extend to other features that rely on the Microsoft Federation Gateway.
If you run the Test-FederationTrust cmdlet, you receive an error message that indicates that the Delegation token has validation issues. For example, you receive an error message that resembles the following:
Type : Error
Message : Failed to validate delegation token.
Additionaly, you might receive one of the following error messages in the Exchange Web Services (EWS) Responses:
To resolve this issue, refresh the metadata by running the Get-FederationTrust | Set-FederationTrust –RefreshMetadata command.
Note: This command updates the information used for the Federation trust. You won't have to re-create organization relationships or sharing policies. The commands must be run in the target environment of the Free/Busy request.
To do this, follow these steps:
- Open the Exchange Management Shell on the on-premises Exchange server.
- Run the following cmdlet:
Get-FederationTrust | Set-FederationTrust –RefreshMetadata
To run the procedure in the "Solution" section as an automated task and prevent future issues, open a command prompt on the Exchange server, then run the following command. Doing this updates the Federation trust daily.
Schtasks /create /sc Daily /tn FedRefresh /tr "C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe -version 2.0 -command Add-PSSnapIn Microsoft.Exchange.Management.PowerShell.E2010;$fedTrust = Get-FederationTrust;Set-FederationTrust -Identity $fedTrust.Name -RefreshMetadata" /ru System
Still need help? Go to Microsoft Community or the Exchange TechNet Forums.