Freelance 2016 SP1 FDT error
You need to install 2016SP1RU03 or higher before importing from the version you upgraded from. That roll-up will fix the issue with FDT_Root object. That object is used to carry a DTM Multiplexer object by which you can have a seperate HART line connection from Freelance Engineering to your HART devices. This has nothing to do with DTMs connected to devices on the PROFIBUS and was released only for certain projects in the past.