IPhone – Transferring all music from iPhone to iPhone

iTunes uses an internal database for your song list. Move the songs you added manually from Finder to the Desktop (for example).

Check in iTunes settings that it's set to let iTunes manage the Music Library.

Open iTunes and drag and drop the song folder on iTunes (either the window or the icon in the Dock).

iTunes will then copy them and add them to its library.

You can now delete the songs you have on your Desktop.

1. check if you have relocated songs.
2. check if your files can be rewritten.

I use self-written python program to remove stale content.

import win32com.client
itunes= win32com.client.Dispatch("iTunes.Application")
ITTrackKindFile=1
mainLibrary = itunes.LibraryPlaylist
tracks = mainLibrary.Tracks
numTracks = tracks.Count
deletedTracks=0
batch_size = 90 
deleted = []
while True:
  while numTracks  !=0:
   currTrack=tracks.Item(numTracks)
   if currTrack.Kind == ITTrackKindFile:
       if currTrack.Location == "":
         deleted.append(currTrack)
   numTracks-=1
   for track in deleted:
      track.Delete()
      deletedTracks+=1
   del deleted[:] # free memory and close handles
   if not numTracks:
     break

if deletedTracks > 0:
if deletedTracks == 1:
  print "Removed 1 dead track."
else:
  print "Removed " + str(deletedTracks) + " dead tracks."
else:
  print "No dead tracks were found."