I found another solution to loss of local music library that occurred with the “upgrade” of the Sonos app.  I tried the Sonos suggestions to change properties of the folder where my music resides, and still received the dreaded 923 error message that the Sonos app could not access that folder.

My solution was to download the Plex media player for my Windows 11 computer.  This is a free application. You create an account and download the Plex app.  This media player was able to read my extensive library of MP3 files on my computer.  After choosing Plex as the music source, I can access my full library of music from the Sonos app.

I found this to be relatively pain free.  Here are some tips:

When configuring the Plex media player, be sure to authorize remote access (settings → remote access).   You will need to let Plex know where the name of the directory where you keep your music.  Plex will build a library dataset, which took quite awhile as I have a large collection of mp3s.

From within the Sonos app, choose the Plex media player as a streaming source for Sonos.  I did not understand that when Sonos asks for a password, it is asking for your Sonos password, not your Plex password, to authorize this “subscription.”  My other stumbling block was that I had not allowed remote access in Plex.  This is required.

I now have full access to my music library from the Sonos app.  It has all of the same features the Sonos had before the “upgrade.”   It is also possible to use Plex and play the result through your Sonos system, but this requires upgrading to the “paid” version of Plex.  This is either a one-time payment of $5 or a $5/month subscription.

I highly recommend this method of getting around the deficiencies of the Sonos software.  I did not need to adjust any Windows system properties to make this work!