If memory serves, you need to use the ‘export to .xml’ function in iTunes, in order to create the necessary file that Sonos needs to read. Once you’ve done that, you’d want to run the library update from within the Sonos  controller as well. 

Hello Airgetlam

Thank you so much for your help

I tried to

→ MUSIC / LIBRARY / EXPORT LIBRARY (.xml)

→  I put the .xml in the folder where all my music is and try to update my libray within the Sonos Controller.

Sadly, same problem. The new playlists aren’t visible by the Sonos app.

Don’t hesitate If you think to another solution.

regards

I have the same problem, so hoping for a solution…..
I already tried updating Sonos controller, and giving it Full Disk Access in Security and Privacy Preferences. 

It’s 16 months since macos Catalina and this problem was identified on these forums.
Why hasn’t it been fixed?

Hi @nigelsmith 

Are you still having this problem?

Until the advent of the “iTunes app” becoming the “Music” app, playlists were stored as a file called “"iTunes Music Library.xml" or “iTunes Library.xml” in the parent folder. The “Music" app no longer creates this file. As Sonos speakers try to import the playlists from the xml file which “Music" no longer creates, when you now index music the Sonos App first reads the “Music" app’s playlists (from where ever they are now stored) and writes the xml file in the shared folder so that when the speaker accesses the folder via network, it can find that xml file and import the playlists on it. This happens because the speakers cannot access the new location of where those playlists are stored via the network share. 

Removing this file can often fix problems with missing/extra/out-of-date playlists, but we recommend you rename the file instead of deleting it, in case you need to back-track. Once you do that, reindex from the Sonos app.

There’s more detail on this other thread:

Hi Corry,

Thanks for responding. I’m still having the problem - every morning the scheduled music library update produces the error message, and I still have no Music playlists in Sonos. I followed your advice and a new iTunes Music Library.xml was created, but I still get “An unexpected error occurred while importing playlists” and an empty imported playlists folder :(

The Music folder which is the one ‘shared with Sonos’ contains just one file - “Music Library.musiclibrary”

https://support.sonos.com/s/article/3282?language=en_US
 

“Access to Smart Playlists, music videos, and artist posts from Connect are only available within the Apple Music app and are not supported on Sonos.”
However I’m not getting ANY playlists from my library, smart or otherwise.
I haven’t added Music as a service in Sonos because I don’t want or use their streaming service. Could this be a factor?

iTunes used to have two ways for 3rd party apps to access its library contents (playlists, etc): a copy of the library in an XML file (legacy), and the iTunesLibrary API. Apple has been urging 3rd party app developers for years to use the API, but clearly not all of them have had their eyes on the ball.

From Apple Music on Catalina onwards the API is the only way to access it now. Which, ironically, is still called iTunesLibrary

It turns out that even a free Android app like Rocket Player can access the playlists in Music with no problems, but Sonos can’t.
Lame.