After deploying a Lync 2013 pool alongside an existing Lync 2010 deployment, users were unable to join conferences created by users registered on the 2013 pool. They would get the error “Conference Error”. This affected users who were moved from the 2010 pool and new users created on the 2013 pool.

When trying to change the Lync meeting options in Outlook or trying to reset the Assigned Conference Information via the Dial-in conference settings page it would generate an error.

Also, when calling the dial-in conference number and entering the conference ID you would get the message: “Sorry I can’t find a meeting with that number, try entering your conference ID again and then press #”.

The Lync 2013 Front End event logs had the following event:

Log Name:      Lync Server

Source:        LS MCU Factory

Date:          09/04/2013 17:22:32

Event ID:      51048

Task Category: (1021)

Level:         Error

Keywords:      Classic

User:          N/A

Computer:      fe2013-1.domain.local

Description:

McuFactory could not find the pool associated with one of the conference directories.

Failed to read pool FQDN associated with conference directory 11.

Cause: The pool associated with the conference directory does not exist anymore.

Resolution:

Conference directories without a valid pool associated can be deleted using management tools.

To fix, if you run the command “Get-CsConferenceDirectory” it will return which conference directories are in use.

Get-CsConferenceDirectory | select Identity,ServiceID

--------                                ---------
1                                       UserServer:fe2010.domain.local
11                                      BackCompatSite-UserServices-1
12                                      UserServer:fe2013-1.domain.local
13                                      UserServer:fe2013-2.domain.local

As you can see from the output above, there is still a conference directory from the old OCS 2007 R2 environment (BackCompatSite). The BackCompatSite was deleted from the Lync 2010 Topology a long time ago so I’m not sure why it is still referenced. As you can see this has the same Identity as the error on the Lync 2013 FE server (Failed to read pool FQDN associated with conference directory 11). To resolve this I deleted the BackCompatSite Conference Directory by running the command below (where 11 is the Identity of the Conference Directory I want to delete):

Remove-CsConferenceDirectory -Identity 11 -Force

After I restarted the Lync 2013 FE server, users were able to create and join conferences. The meeting options in Outlook, Dial-in conferencing settings page and dial-in conference ID’s all worked too. Looks like Lync 2010 was fine with this old BackCompatSite Conference Directory, but Lync 2013 wasn’t!