EWS Not Deployed on the Lync 2010 Configuration Tab

EWS Not Deployed on the Lync 2010 Configuration Tab

Note: I have tried to make this web page one stop shop by collecting useful solutions around the internet.Please update me using comments for any kind of useful information for that issue.

This issue has been faced my many guys deploying Lync Server 2010. I have also faced this issue on couple of deployment of Lync Server 2010 at client-side.

what are the symptoms?

- Repeatedly prompting for enter credentials while using Lync 2010 client.

- and RED sign appears on the bottom of Lync 2010 claiming “Exchange Connection Error”.

-When you access Lync 2010 client configuratiob tab using Ctrl+Right Click on Lync sign on the taskbar, You will see EWS not deployed in EWS information.

what are the causes?

- when you have different SIP/SMTP addresses for a user , MAPI sync will not able to take place, and if EWS is also not depoyed correctly, this error will prompt, if EWS is deployed correctly , it will not care about MAPI sync, and the error will not appear.

- When you have same SIP/SMTP addresses this issue may not appear even if you dont have EWS deployed because MAPI sync will do that job. but for better integration to take place it is mandatory to have EWS deployed. to check EWS you can also verify services provided using EWS like MailTips, if its working or not.

- OR When you have migrated OCS 2007 R2 to Lync Server 2010 for details http://blog.rudikersten.com/2011/05/31/lync-client-prompts-for-credentials-when-connecting-to-exchange-services/

what are the resolutions?

if you google this issue over the internet , you will get confuse of different types of resoltion available for that issue:

- if you a Lync Online user install this update: http://support.microsoft.com/kb/2503538

- if you migrated infrasturcture from OCS to Lync follow him : http://blog.rudikersten.com/2011/05/31/lync-client-prompts-for-credentials-when-connecting-to-exchange-services/

-if you have on Premises greenfield infrastructure with Lync 2010 / Exchange 2010 try this out:

  • Manually access EWS external URLs, if this URL will directly show TMG logon page and require username and password. So, this issue should be related to the TMG publish.
  • Also , If both internal and external URL is set to “https://mail.company.com/EWS/Exchange.asmx“. Is there an A record for “mail.company.com” on internal DNS? If there isn’t ,please set the internal URL to your internal CAS FQDN by running following commands:-set-organizationConfig -EwsEnabled $true – EwsApplicationAccessPolicy EnforceBlockList

if above cmdlet solves your issue than its OK , if not plz run cmdlet below

-Set-WebServiceVirtualDirectory –Server CASName –InternalURL ”https://internalCASFQDN/EWS/exchange.asmx

    • Before focusing on TMG, please check the following configuration:

Go to CAS and open IIS manager->go to EWS virtual directory and make sure both “anonymous” and “Windows integrated” authentication are selected.Please restart IIS by running IISRESET command.In an internal user’s computer, open IE and access EWS URL to make sure its works fine.

  • On TMG(Reverse Proxy) please verify no pre-authentication required on EWS URL.








Thanks and Regards,
Farrukh Qazi
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