We’ve been hard at work on some significant improvements to music metadata in Plex, and as part of that effort, we’re reworking some parts of the system that automatically grabs all that sweet artwork and other metadata that make your music library awesome. This change will impact the ability to add new music to Plex Premium Music libraries on older Plex Media Servers:
Starting July 1, Plex Media Server version 1.15.8 or higher will be required to continue to add music to Premium music libraries.
If you’re currently running an older server version, make sure you grab and install the latest release from https://www.plex.tv/media-server-downloads/ to keep things running smoothly.
Also: Please note that starting July 1, Plex Mix and the ability to create new Premium Music Libraries will be temporarily unavailable. We’re working on some big improvements in these areas as well. New (standard) music libraries will be able to take advantage of these features when they’re available. Stay tuned!