Music hangs on Saving Music Library

Here's an update on the slow progress I've been making.

As an experiment, I exported the library to an XML file and I made a clone of the original Media Library folder on an external SSD. I then edited the Library.xml file so the path pointed to the external volume*; created a new blank music library on Ventura, and imported that XML into it. It kind of worked, but indicated it got some errors.

*Before I imported it, I opened it with Bbedit to edit the path. Bbedit gave me an alert about malformed UTF-8. Which I just ignored, but turns out it was significant.

I used 'xmllint' to look for issues. Sure enough, there were a couple files that had invalid UTF-8 in their metadata. xmllint tells you the line number of the offending data, I then scrolled to that line in Bbedit and scrolled back a few lines to determine the track / artist with the issue. I then went into Music.app and edited the Metadata (with Song -> Info) and either removed the offending field (2 were in Genre, the other in the track filename).

I exported the library again, and this time xmllint showed the file was valid.

Great! Although it's still taking forever to load into the new instance, so I don't know if it truly works. But the bad unicode may be what was crashing it when it goes to save the library. I'll keep you posted.

Here's some comments I got from jwz (.org), who had done some open source tools working with the iTunes library file:

"HFS+ would normalize Unicode characters in pathnames using the NFKD form, but APFS does not normalize at all (arbitrary bytes are allowed) and I believe that iTunes/Music.app normalizes using the NFKC form prior to writing to APFS. So depending on when and where that file was first "kept organized", it might be encoded differently, and you can end up with two different files that are equivalent Unicode strings once normalized."

This might explain issues moving to to a NAS as well.

Here's an interesting datapoint. I just started with a blank library on the Ventura machine, and manually dragged all the files into a new, blank library. 270k files. Took a while but eventually loaded. Spot checked them, the seemed to all be there.

Then I quit music.

The "Saving Library" dialog came up for about 15 minutes and then the app exited normally.

Except the library file wasn't updated.

And when reopening it, nothing was there.

It failed silently. I'm trying again, bringing about 1/4the of the library at a time, and will report back on how that goes. I'm not sure if it's something in the metadata of one of the tracks, or the size of the library.

I did experiment with bringing in just a few thousand tracks and that saved properly and was there when reopening.

Here are some screen shots from Activity Monitor during the time it's stuck saving the Music Library: