SWEET 
This will be easy to resolve.
I am writing these instructions presuming you want your existing server data (which still sits in the Plex shared folder, to be upgraded / migrated to DSM 7.
If that’s not the case or you have special request, please let me know.
Undoing what happened
-
Uninstall the current DSM 7 package with the ERASE option to remove this errant/rogue DSM 7 package
-
Manually set the “Full Control” permissions for the Plex shared folder
- This step will require approximately 2-3 minutes for each 1000 media items you have indexed. Don’t be surprised if it takes quite a while. I’ve seen a few extreme cases (Plex share was 500GB in size) that needed several days.. yes — DAYS)
When this step is complete, all the permissions will be set for migration to automatically start.
When you now Manual Install PMS again, it will go to “Installing” and sit there.
Be patient with it. It’s going to walk through each file in the shared folder and making it ready.
Do not be alarmed if DSM 7 gives you “Operation Failed” or similar. DSM 7 has a security timer which is fussy/flaky.
The way to confirm it’s still installing –
-
In a new session , Plex shared folder will contain “Migration.log” which will appear about 2-3 minutes after it starts.
-
Resource Monitor - Task manager / Processes – will show username “PlexMediaServer” (PlexMedia+) running tasks.
Whatever you do, don’t restart DSM until this is complete as you could be left with a split metadata / database .. which is a mess to clean up.
IF
If, when you start this process, it says “Installation successful” again very quickly –
- Check the Plex share and make certain it’s empty
- If NOT EMPTY – Uninstall + ERASE again
- Manual Install again
(sometimes DSM makes 2 copies)
