I know there have been other event id 87 questions posted, but none of them have the description that I am experiencing. Log Name: Application Source: MSExchange OWA Date: 6/18/2012 1:04:59 PM Event ID: 87 Task Category: InstantMessage Level: Error Keywords: Classic User: N/A Computer: CASHUB-01 Description: An exception was thrown while attempting to load the IM provider .dll file. File: C:\Program Files\Microsoft\Exchange Server\V14\ClientAccess\OWA\bin\Microsoft.Rtc.UCWeb.dll The local host name specified is not valid. Parameter name: localHost Thanks in advance.

Hello chireader, Since the error is "The local host name specified is not valid.", I suggest you follow this document to check whether you have inputted the right parameters to configure Lync and Exchange IM integration. Lync and Exchange IM Integration http://blog.schertz.name/2010/11/lync-and-exchange-im-integration/ Thanks, Evan Liu TechNet Subscriber Support in forum If you have any feedback on our support, please contact tngfb@microsoft.com Evan Liu TechNet Community Support

Thanks for the reply. I am getting this error after I do the IIS reset on the cashub server. Per the instructions on the post you supplied this step comes BEFORE any configuration on LYNC. So this makes me think changing anything on LYNC is not going to resolve my issue, or at least specifically this invalid host error. I have a public cert with all the Exchange hosts/names in the SAN, which is why I believe I am not getting a cert specific error, rather this invalid host name situation. The pubic cert does not have the lync host name. Is this required? Would that be the cause of the invalid host error? Or, is the invalid host refering to the cashub server names? I have a WNLB setup and a 2 node CAS array setup. Here are the url's for both of my CAS servers: InternalUrl ExternalUrl ----------- ----------- https://cashub-01.domain.com/OWA https://mail.domain.com/owa -- CAS#1 InternalUrl ExternalUrl ----------- ----------- https://cashub-02.domain.com/OWA https://mail.domain.com/owa -- CAS#2 CAS#1 IM info InstantMessagingCertificateThumbprint InstantMessagingServerName InstantMessagingEnabled InstantMessagingType ------------------------------------- -------------------------- ----------------------- -------------------- D410712F11809694BF213C39B.... lync.domain.com True Ocs CAS#2 IM info InstantMessagingCertificateThumbprint InstantMessagingServerName InstantMessagingEnabled InstantMessagingType ------------------------------------- -------------------------- ----------------------- -------------------- D410712F11809694BF213C39B... lync.domain.com True Ocs I created a mulitple computer lync applicatin pool named mail.domain.com/owa with my two CAS servers under it. I suppose I should have included this info in my first post. Thanks again.

If you use CAS array, I think it should use the FQDN of CAS array. The TrustedApplicationPoolFqdn value should be your CAS array. Thanks, Evan Liu TechNet Subscriber Support in forum If you have any feedback on our support, please contact tngfb@microsoft.com Evan Liu TechNet Community Support

Thanks for the response, but as I stated I am getting this event logged when doing the IISrest on the CAS. This configuration preceeds any configuration on Lync. Again, seems like this is some type versioning issue or unknown issue. I finally got a answer back from PS stating that it could possibly be that my CAS servers names begin with a numeral. I am going to build a third cas and place it in our CAS array and see if this new server works. I'll post the results.

Thanks for your reply. You can follow that document to configure the new CAS, then check it work or not. Best regards, Evan Liu TechNet Subscriber Support in forum If you have any feedback on our support, please contact tngfb@microsoft.com Evan Liu TechNet Community Support

This issue was the computer name of CAS servers. They cannot begin with a number. Created a new CAS and added it the exiting CAS array using our current public certificate. Updated the lync pool with the additional CAS server. IM integration works on the new CAS server named with a letter. The other two named with a number still do not work and have the error 87 event on IISrest.