We are in a 2010 to 2013 migration. We have a set up a new address book on 2013 and assigned to the 2013 database. On the users who are now moved to the 2013 database, when they try to force their Outlook client (2013 in this case) to download an address book from "Send/Receive, Send/Receive Groups, Download address book, they get the following error:
Windows authentication is enabled on the OAB directory on the server (we haven't touched any of the settings here). Anything stand out as to what would cause this?