The PMS upgrade migration process starts automatically when it detects a Plex shared folder.
There are very few ways this can fail.
The most common is when permissions for the Plex shared folder have been manually set to something non-standard. This becomes a problem the DSM 7 installer doesn’t have administrator privileges anymore. (part of what changed in DSM 7).
The reason you’ll get a duplicate name is because the default server name is the NAS name (hostname)
Did you review the How-To to familiarize yourself with the process?
