(Also posted at forums.msexchange.org ) Hi guys, Just recently installed a fresh Exchange 2010 environment (We are currently using Domino and will be migrating to Exchange, so no prior Exchange setups to trip us up) and everything appears to be in order, except for the Offline Address Book. When I try to generate it, the following 2 errors appear in the event log on the mailbox server I execute the command from: OABGen failed to read objectGuid attribute from OAB object '/o=<org name>/cn=addrlists/cn=oabs/cn=<OAB name>' in Active Directory. Please check security settings on this object. OAB generation will not be performed. OABGen encountered error ffffffff while initializing the offline address book generation process. No offline address books have been generated. Check the event log for more information. From the information I gathered online, this used to be a problem in Exchange 2007 running in a clustered environment - this isn't the case here. All roles are running Exchange 2010 Update Rollup 1 (version 14.0.639.21) on Server 2008 R2. Mailbox servers on dedicated hardware. CAS and HUB on shared hardware. Autodiscovery works, but OAB directory on CAS is of course empty, as no OAB has ever been generated. Thank you in advance for any help you might be able to provide!

I would go ahead and install the latest RU 4 on your server. As far as the OAB goes, go through this link and make sure everything is configured right: http://technet.microsoft.com/en-us/library/bb124719.aspx If you still have issue, I would create a new OAB from scratch...no harm in that. http://technet.microsoft.com/en-us/library/bb124339.aspxTim Harrington - Catapult Systems - http://HowDoUC.blogspot.com

Thanks for your reply, TW. I should have mentioned that I have already tried to create a new OAB from scratch - same issue. I can't believe I didn't check to see if there were any new RU's available - I just went by what was available through Microsoft Update :-/ I'll apply it and see where that takes me! thanks

Yup - UR4 resolved the issue. Thanks so much Tim!