I've got the dreaded "iPhone is synced with another iTunes library. Do you want to erase and sync this iPhone?" message in iTunes, preventing me from managing the music on my phone. I'm not sure how this happened - perhaps I created a new iTunes library at some point and have subsequently deleted the old one (as I've tried all the libraries I can find, including from backups) - although I secretly suspect it's just iTunes being hateful 
In any case, when this has happened to me in the past (e.g. switching to a new computer, sharing a phone across multiple libraries), I've been able to change the iTunes library ID to match the phone (either by editing the library file in a hex editor, or by editing the XML, corrupting the library file and allowing iTunes to recreate the library from the XML). With iTunes 12, I've tried every tutorial I can find but have had no luck - no matter what I try, iTunes seems to think the library is corrupt and empties the library, in the process giving it a new library ID.
Has anyone successfully managed to modify the library ID of an iTunes 12 library? If so please share how! I'd rather not have to restore my phone from scratch if I can avoid it, partly because I just think it's ridiculous to have to do that!
<rant>The link between the iTunes library and the iPhone is honestly the one thing that periodically makes me want to switch phone platforms - I understand why it's there for syncing, but for those of us who prefer to manage everything manually, I wish we could disable it! Does anyone know a good music player app for the iPhone with its own library that can be managed independently of iTunes?</rant>
In any case, when this has happened to me in the past (e.g. switching to a new computer, sharing a phone across multiple libraries), I've been able to change the iTunes library ID to match the phone (either by editing the library file in a hex editor, or by editing the XML, corrupting the library file and allowing iTunes to recreate the library from the XML). With iTunes 12, I've tried every tutorial I can find but have had no luck - no matter what I try, iTunes seems to think the library is corrupt and empties the library, in the process giving it a new library ID.
Has anyone successfully managed to modify the library ID of an iTunes 12 library? If so please share how! I'd rather not have to restore my phone from scratch if I can avoid it, partly because I just think it's ridiculous to have to do that!
<rant>The link between the iTunes library and the iPhone is honestly the one thing that periodically makes me want to switch phone platforms - I understand why it's there for syncing, but for those of us who prefer to manage everything manually, I wish we could disable it! Does anyone know a good music player app for the iPhone with its own library that can be managed independently of iTunes?</rant>