Hi All, I am having random users periodically losing connection to the exchange server. I am seeing a lot of Source: MSExchange Availability Event Event ID: 4002 This is a detailed description of the event. can anyone shed any light?

Process 2416: ProxyWebRequest CrossSite from S-1-1-0 to https://**mail02.***.nche.edu/EWS/Exchange.asmx failed. Caller SIDs: NetworkCredentials. The exception returned is Microsoft.Exchange.InfoWorker.Common.Availability.ProxyWebRequestProcessingException: System.Web.Services.Protocols.SoapException: The authenticated user doesn't have sufficient privileges to issue this request.
   at System.Web.Services.Protocols.SoapHttpClientProtocol.ReadResponse(SoapClientMessage message, WebResponse response, Stream responseStream, Boolean asyncCall)
   at System.Web.Services.Protocols.SoapHttpClientProtocol.EndInvoke(IAsyncResult asyncResult)
   at Microsoft.Exchange.InfoWorker.Common.Availability.Proxy.Service.EndGetUserAvailability(IAsyncResult asyncResult)
   at Microsoft.Exchange.InfoWorker.Common.Availability.FreeBusyApplication.EndProxyWebRequest(ProxyWebRequest proxyWebRequest, QueryList queryList, Service service, IAsyncResult asyncResult)
   at Microsoft.Exchange.InfoWorker.Common.Availability.ProxyWebRequest.EndInvoke(IAsyncResult asyncResult)
   at Microsoft.Exchange.InfoWorker.Common.Availability.AsyncWebRequest.EndInvokeWithErrorHandling(). The request information is ProxyWebRequest type = CrossSite, url = https://***mail02.***.nche.edu/EWS/Exchange.asmx
Mailbox list = <*****, Peter>SMTP:P*****@A***NET.EDU, Parameters: windowStart = 5/1/2015 12:00:00 AM, windowEnd = 7/1/2015 12:00:00 AM, MergedFBInterval = 30, RequestedView = FreeBusy
. ---> System.Web.Services.Protocols.SoapException: The authenticated user doesn't have sufficient privileges to issue this request.
   at System.Web.Services.Protocols.SoapHttpClientProtocol.ReadResponse(SoapClientMessage message, WebResponse response, Stream responseStream, Boolean asyncCall)
   at System.Web.Services.Protocols.SoapHttpClientProtocol.EndInvoke(IAsyncResult asyncResult)
   at Microsoft.Exchange.InfoWorker.Common.Availability.Proxy.Service.EndGetUserAvailability(IAsyncResult asyncResult)
   at Microsoft.Exchange.InfoWorker.Common.Availability.FreeBusyApplication.EndProxyWebRequest(ProxyWebRequest proxyWebRequest, QueryList queryList, Service service, IAsyncResult asyncResult)
   at Microsoft.Exchange.InfoWorker.Common.Availability.ProxyWebRequest.EndInvoke(IAsyncResult asyncResult)
   at Microsoft.Exchange.InfoWorker.Common.Availability.AsyncWebRequest.EndInvokeWithErrorHandling()
   --- End of inner exception stack trace ---
. Name of the server where exception originated: ***MAIL01. Make sure that the Active Directory site/forest that contain the user's mailbox has at least one local Exchange 2010 server running the Availability service. Turn up logging for the Availability service and test basic network connectivity.

Could this be related to my issues? Any suggestions?

Thank You

• Edited by nickels_1050 Wednesday, May 27, 2015 4:21 AM

Hi Nickels,

I recommend you refer to the following methods to troubleshoot the issue:

1. Check if it is a network issue:

Use the Ping or PathPing command-line tools to test basic connectivity. Use Ping to isolate network hardware problems and incompatible configurations. Use PathPing to detect packet loss over multiple-hop trips.

How to troubleshoot network connectivity problems. 

2. Please refer to the following article if it is a cross site access, it may give you some hints:

http://blogs.technet.com/b/davmcg/archive/2013/09/24/cross-forest-availability-what-s-trust-s-got-to-do-with-it.aspx

https://social.technet.microsoft.com/Forums/exchange/en-US/f32ab2a6-a8e1-4e87-8f34-55131fdf8151/cross-ad-site-free-busy-availability-issue

Best regards,

Is there a load balancer in front of the Exchange servers?  If so, check the affinity rules to see if this is a point where outlook is hopping between servers and disconnecting/reconnecting since no affinity or the wrong type of affinity is set.