As pointed out in an article by The Verge, DJs who relied on iTunes are facing problems after updating their systems to macOS Catalina, that not only marks the end of iTunes after nearly two decades, but also removes XML file support while moving native music playback on Macs over to the official Music app in a new library format.
For those who aren’t familiar, XML file support is a popular organizational feature for DJs who use it to sort tracks into playlists and utilize the “Share iTunes Library XML with other applications” option to transmit data between apps. But after updating to Catalina, lack of XML has broken communication between the app and many existing DJ software.
Apple has now also recommended that if a customer is reliant on XML files for DJing, they should avoid updating to Catalina until developers update their apps.
According to Apple if a customer is reliant on XML files for DJing, they should avoid updating and continue using their preferred software on macOS Mojave until developers push out fixes (some, like Serato, are already trying out new beta versions tailored for Catalina). iTunes on Windows has not changed, so apps on Microsoft’s platform should function as normal.
So as of now, if you have sorted your music in your iTunes playlists over the past many years, upgrading to Catalina will likely destroy that all.