Event ID:4002;

Question

We are seeing the following error in our On-Premise Exchange server (2013) which is in a hybrid setup. We don't have any users complaining of the Free/Busy schedule not working and our testing shows it is working.

Process 18424: ProxyWebRequest FederatedCrossForest from S-1-5-21-4055847394-2181167018-4057280825-11054 to https://outlook.office365.com/EWS/Exchange.asmx failed. Caller SIDs: OAuth. The exception returned is Microsoft.Exchange.InfoWorker.Common.Availability.ProxyWebRequestProcessingException: Proxy web request failed. ---> System.Net.WebException: The request failed with HTTP status 404: Not Found.
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.EndGetUserPhoto(IAsyncResult asyncResult)
at Microsoft.Exchange.InfoWorker.Common.UserPhotos.UserPhotoApplication.EndProxyWebRequest(ProxyWebRequest proxyWebRequest, QueryList queryList, IService 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: MREDMEXCH12. 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.

Answer 1

Hi @Daniel Kaliel

What's your on-prem Exchange server CU version? And where are your users located now, on-prem or cloud?

Could you please share the result of the below command in your on-premise organization

Get-OrganizationRelationship | FL Identity, TargetSharingEpr  

I see the error that free/busy information for some mailboxes which were recently moved to O365 is not available, and will get the similar error log like yours.

That issue is caused by Office 365 Autodiscover service which returns incorrect endpoint for calendar sharing for some mailboxes. To fix the issue you could configure TargetSharingEpr property in Organization relationship in your on-premise organization. It will force connection directly to correct O365 endpoint without using Autodiscover.

 Set-OrganizationRelationship -Identity "On Premises to Exchange Online Organization Relationship" -TargetSharingEpr "https://outlook.office365.com/ews/Exchange.asmx"  

In addition, have you checked the freebusy result in ExRCA tool, does it return any error information?
https://testconnectivity.microsoft.com/tests/FreeBusy/input

Here is also an article introduces about Demystifying Hybrid Free/Busy: Finding errors and troubleshooting

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Answer 2

We are on Exchange 2013 CU23 with the July security update installed. The vast majority of users 95%+ are still on premise with only a small test group in Exchange Online. Here are the results of the command:

[PS] C:\Windows\system32>Get-OrganizationRelationship | FL Identity, TargetSharingEpr

Identity : On-premises to O365 - 106de261-21f5-44b3-bc2e-b1ba3d3efa98
TargetSharingEpr :

The free/busy test came back with no errors:

Answer 3

I've run that and will post back if the error is gone.

Answer 4

Hello,

I know this post is a bit older. How was the problem solved ? What was the cause ?

Thank you very much !