Lync EWS Broken During Exchange 2013/2007 Transition


During the transition to Exchange 2013 from Exchange 2007, Exchange Web Services (EWS) integration for Lync will be unavailable for users whose mailboxes remain on Exchange 2007.

MAPI integration via Outlook will continue to be available.

Microsoft has confirmed that this is a known issue, and the only work around at this time is to rely on MAPI integration via Outlook, or migrate the users to Exchange 2013

Microsoft also stated that this is only an issue with Exchange 2007/2013 coexistence, and will not impact 2010/2013 migrations.

If Outlook is not launched, the following error message will be displayed.  Other possible EWS integrations errors may also be displayed.

“Lync cannot connect to the Exchange server.  Please try signing out and signing back in.  Outlook contact and calendar information will be unavailable until the connection is restored.”




If you open the Lync Configuration Information, you will see that the EWS Information is not displayed, and the status is “EWS not deployed.”



You will also notice that there is no information listed for the EWS Internal URL or EWS External URL.




NOTE: This is only an issue for mailboxes which still remain on Exchange 2007.  Mailboxes already migrated to 2013 are not impacted, and the issue resolves itself when a 2007 mailbox is migrated to 2013.

During the transition from Exchange 2007 to 2013, the AutoDiscover DNS records for Exchange are updated and pointed to the Exchange 2013 CAS.  This is necessary as part of the transition as Exchange 2013 can proxy connections to legacy versions, but Exchange 2007 cannot proxy connections forward to newer versions.

The Lync client retrieves EWS configuration information from the Exchange AutoDiscover service.  When the Lync client is launched, it makes a request to  There are many good posts on this process, so I won’t cover it.

When the Lync client connects to the Exchange 2013 AutoDiscover Virtual Directory, the client receives a 401 Authentication Required.  If the workstation is joined to the domain, it is authenticated via Integrated Authentication.  If it is not domain joined, the client receives an authentication prompt for Basic Authentication.

After authenticating, the Lync client immediately gets an EWS integration error in the bottom right corner of the client, and red exclamation marks on the additional tabs.




If we look at the Configuration Information by holding CTRL and right-clicking the Lync icon in the system tray, we will see the wonderful “EWS Not Deployed” message.




If we open a NetMon trace, we can see a request made to the Exchange 2013 CAS.




Further, if we look at the IIS logs on the Exchange 2013 CAS, we can see the Lync attempt to make a connection, receive the 401 Authentication Required, and subsequently a 200 OK.


2013-12-19 22:01:55 POST /autodiscover/autodiscover.svc &cafeReqId=b5283628-655c-4478-9e3d-d6fa43a3c44a; 443 – OC/15.0.4563.1000+(Microsoft+Lync) 401 1 2148074254 78
2013-12-19 22:01:55 POST /autodiscover/autodiscover.svc &cafeReqId=4a99f3d0-694c-42a3-92cb-cf0a6293034c; 443 domain\test OC/15.0.4563.1000+(Microsoft+Lync) 200 0 0 234


So it appears everything should be working right?.  The Lync client connects to AutoDiscover successfully, and we see the 200 OK.  But the Lync client never pulls down the XML configuration.

Now we can go look at the AutoDiscover log on the Exchange 2013 server.  This can be found at  C:\Program Files\Microsoft\Exchange Server\V15\Logging\Autodiscover.

Low and behold we finally find an error:

ErrorMessage=The SOAP-based AutoDiscover service is not available for mailboxes on Exchange 2007.



Microsoft has confirmed that this is a “Known Issue” at this time, and there is no valid workaround or fix.  The only fix is to migrate the user to Exchange 2013.

One Reply to “Lync EWS Broken During Exchange 2013/2007 Transition”

  1. hi,
    we have exchange 2010, lync 2010 server deplyed in our organization. And on one client using windows 10 with office 2015 (or 2016 ). lync is not saving conversation history . and lync showws exact same prompt as you shown and also .. however in history spooler folder i can see a lot of text files and they have the conversation there. but it is not uploading to exchange server .. checked on owa as well.
    if i login on his syste with my domain account i am also facing same issue.
    however conversation history is working for me on my domain joined windows 7 pc with office 2013.
    on his sytem i repaired office. recreated outlook profile. deleted sip_username folder.

    Please advise

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