With the library folder copied to the new location, you can't select the library at its new location by holding the option key when you open Music?
i was in the same situation barely 4 weeks ago. i have about 40'000 songs in iTunes, maybe 15'000 ripped from CDs, 15'000 manual transfers from LPs at 96khz/24 bit, around 5000 HiRez files from HDtracks and other sources, and around 5000 bought from iTunes. everything except the ones i bought from iTunes are Apple Lossless, the rest is AAC. all the songs that i ripped from CD or LPs have the cover art embedded, same for the HiRez files.
i'm very careful wrt metadata. but the real challenge was that i have more than 1000 cover versions of one and the same song (Fever). maybe 80 percent of these Fever covers have the same song title, the remaing 20 percent are foreign language versions.
i tunes has more than once completely and utterly messed up both, the database and the music files in the past which has led me to have a clean safety copy of all songs on a separate drive sorted by album artist and with artist/album/song in the file name. since all the relevant data plus the cover art is embedded in the individual files, i can in the worst case just re-build the entire collection but would lose all the information that is *not* embedded in the metadata; same goes for playlists etc.
for ten or more years i have kept my entire music collection on a NAS; the library is on the same NAS, too. that way i can use one library on all connected macs which makes it easier to keep the database up to date.
alone the switch from itunes to apple music has kept me from upgrading my computer. late april i was sick of paying adobe creative cloud subscription fees – and being forced to use the 2021 apps… my computer is a souped up MacPro5,1 from september 2012 that i wanted to keep. so i installed Open Core with Monterey 12.6.5 on a new SSD.
the migration from itunes to apple music was far less painful than i feared. here's what i did:
still in mojave i did the following:
created a new folder on the NAS named Apple Music.
option-dragged the library.itl file from the itunes folder to the apple music folder.
shut down the computer.
rebooted with open core into monterey.
opened Apple Music in Monterey, set the prefs for importing and managing music files exacely as i had it on itunes
quit Apple Music
in Monterey's finder, navigated to the folder on the NAS with the copied iTunes library.
right-clicked on the file and chose "Open with…" Apple Music.
that did it.
Apple Music imported and converted the iTunes library to Apple Music with all playlists and other vital information. because the music files were at the same location, Music didn't have to move them.
then came the hard part. i wanted to have a separate Apple Music library with only my 1287 versions of Fever – just to make sure that – if at all – they don't mess up my other songs. it was easy to separate all 1287 versions with an intelligent playlist looking for Davenport/Cooley as composers (i use the composer to separate "my" Fever from other songs with the same name). too bad only that there is no way to export 1000+ songs from an intelligent playlist.
so i ended up opening a second Apple Music library and pulling the 1287 files into the app. for this library, i set the prefs to "import files and copy them to…" – that way i got a separate library with a safety copy of all my covers. since all the vital information is in the metadata, i didn't lose anything but the added / last played data (which is not relevant for this collection).
all in all, the move was a lot easier than i imagined. working with a copy (and not the original) of my iTunes library.itl, nothing could happen that would cost me more than a couple of days reconstruction work…
Apple Music is a lot more robust than iTunes, less bloated and more stable. it is now what iTunes was in the beginning – an app to manage and play music. not as bloated with managing iOS apps, videos etc.
to make a long story short: if you have really solid metadata of your songs and if possible the cover art embedded, drag & drop of the files into the open Music app is actually a very simple and easy way to re-build a music library from scratch. it will not take too long either, because Music is robust enough to cope with you dragging 100+ 10-song albums into Music at once. it will be busy for a while sorting the stuff, but it won't take you more than 1 hour to move a collection of 20k songs into Music if all else fails.
** important before you start the migration **
- make sure that iTunes hasn't messed up your library. it is very well possible (and happened to more than once) that i played a sont in iTunes just to find out that a/ the song is not what the metadata claims, and b/ the cover art corresponds neither to the metadata nor to the music file… you don't want to migrate a music collection with a corrupted data base and the wrong cover art…
- if possible, use your own method of naming the files so that each and every file has artist / album / song title in the file name. that way, you will at least be able to sort wrong songs just by looking at the files in the folder.
- in my experience, both iTunes and Music, are happier if you let them organize the music files (i.e. move the files to one place with one coherent file structure, but NOT rename the files) than keeping audio files in x separate locations and rely on the app to know where they are.
