Hi All, I overhauled the current Volumio Spotify plug-in many years ago as a way of learning how to develop with Node.js. I was taking time off between gigs, but back in the thick of it working in Enterprise software sales now.
I believe the reason the Spotify plug-in is failing is because it relies on the SPOP deamon, a C program that uses Libspotify. Libspotify was deprecated back in 2017 by Spotify, so we knew this day would be coming.
One approach worth looking at is how Michael Herger, the Swiss-based Logitech engineer who single-handedly maintains the Logitech Media Server, created his Spotty plug-in for the LMS: GitHub - michaelherger/Spotty-Plugin: A Spotify plugin for the Logitech Media Server and Squeezebox
He is using Librespot, which does not depend upon Libspotify. He therefore exposes the LMS as a Spotify Connect client. But the way he does this makes Spotify completely integrated in the LMS UI. He also does some other very clever things, like infers Spotify folder structures whereas the Spotify Web API doesn’t support folders. He’s a much better engineer than me.
So since there is an LMS plugin for Volumio, in principle people can install it, the Spotty plug-in into it, and you should be back in business. I haven’t tried it yet so I can’t verify that. I have numerous Raspberry Pis and DACs, some running Volumio, some piCorePlayer with the LMS and Squeezelite. I just verified the LMS Spotty plug-in is still working, as it did not use Libspotify.
I used to work a lot with the open-source Drupal system, as well as working as a Sales Engineer at Acquia, which provides commercial support for Drupal. The Drupal core team decides on a release by release basis which community-contributed modules should be committed to Drupal core, and maintained by the Drupal core team. I believe that which Spotify being a major draw to Volumio - both free and paid versions, it makes sense for the Volumio team to move the Spotify into the core Volumio distribution and maintain and support it.
Since Michael’s Spotty plug-in is open-source, you can probably use it as a starting point.