CMN ExchangeFreeBusyService log file shows contains error, "(401) Unauthorized." (4348097)

CMN ExchangeFreeBusyService log file shows contains error, "(401) Unauthorized."

Notes users are unable to lookup free busy data for Exchange users. The Notes to Exchange free busy requests are making it past QCalCon and to the ExchangeFreeBusyService on the CMN Free Busy server. In the ExchangeFreeBusyService log file, the following errors can be seen:

2013-06-18 13:56:47,052 [22] ERROR ExchangeFreeBusyConnector - GetFreeBusyInfo()
Microsoft.Exchange.WebServices.Data.ServiceRequestException: The request failed. The remote server returned an error: (401) Unauthorized. ---> System.Net.WebException: The remote server returned an error: (401) Unauthorized.
   at System.Net.HttpWebRequest.GetResponse()
   at Microsoft.Exchange.WebServices.Data.ServiceRequestBase.Emit(HttpWebRequest& request)
   at Microsoft.Exchange.WebServices.Data.ServiceRequestBase.ValidateAndEmitRequest(HttpWebRequest& request)
   --- End of inner exception stack trace ---
   at Microsoft.Exchange.WebServices.Data.ServiceRequestBase.ValidateAndEmitRequest(HttpWebRequest& request)
   at Microsoft.Exchange.WebServices.Data.SimpleServiceRequestBase.InternalExecute()
   at Microsoft.Exchange.WebServices.Data.GetUserAvailabilityRequest.Execute()
   at QuestSoftware.CMX.API.Core.FreeBusyExchange.EwsHelper.GetUserAvailability(SmtpEmailList userEmailAddressList, DateTime startTime, DateTime endTime)
   at QuestSoftware.CMX.API.Core.FreeBusyExchange.ExchangeFreeBusyConnector.GetFreeBusyInfo(SmtpEmailList exchangeUserEmailAddressList, DateTime requestStartDateTime, DateTime requestEndDateTime)

Workaround 1:

In this case, this issue was resolved by entering an "Exchange Username" and "Exchange Password" on the Exchange Free/Busy settings screen in the CMN management console.

Workaround 2:

If the "Exchange Username" and "Exchange Password" on the Exchange Free/Busy settings screen are already configured, then try logging into the Office 365 portal using these credentials.

This environment recently had an load balancer installed in front of the Exchange CAS servers which required the credentials to be specified. Previously, this environment did not require these credentials to be configured.