We should sync the LDAP attribute "preferredDeliveryMethod", the code is already implemented in a branch. This requires adding a new property to UDM modules and suffers from Bug 50080. The idea to handle this is to merge this code for a UCS release instead of an erratum, and warn users in the release notes and recommend removing the extended atttribute. Or we could add a check in the preup.sh and block the update if a conflict like Bug 50080 is detected.
This issue has been filed against UCS 4.4. UCS 4.4 is out of general maintenance and components may have vastly changed in later releases. Thus, this issue is now being closed. If this issue still occurs in newer versions, please use "Clone this bug" or reopen this issue. In this case please provide detailed information on how this issue is affecting you.