I'm migrating my databases from FileMaker Server 15 on an old Mac to FileMaker Server 16 on a new Mac. I thought this would be pretty simple, copy all the files from the old .../Data/Databases/ folder to the new one. I did that, including the RC_Data_FMS folder which (I think) is where all the external container data (secure) is stored. The databases are accessible from the new server as expected. However, on the new server, none of the externally stored container data is accessible. (Container fields that should contain e.g. PDFs are just empty, and attempts to store new data in container fields fail silently.)
What extra steps do I need to take to migrate my external container data to the new server along with my databases?