I have been upgrading my RTM Exchange 2013 to CU1. I have 2 multirole servers in DAG. I have started to install CU1 on the node hosting only passive copies of databases. In step 1 of 18. Organization preparation from GUI setup it generated error as it can be seen in the following Picture.
Recommended workaround from Microsoft is to delete the following object from AD configuration partition using AdsiEdit
CN=ClassificationDefinitions,CN=Rules,CN=Transport Settings,CN=<Your organization name>,CN=Microsoft Exchange,CN=Services,CN=Configuration,DC=<domain>i,DC=<com>
The object is also shown in the Picture
After deletion setup can be restarted. Object is then re-created and setup can continue.