Apple’s latest desktop operating system update, macOS Catalina, will mark the official end of iTunes after nearly two decades. But that transition is proving to be complicated for a certain subset of Mac users who’ve relied on the software to help manage their jobs: DJs.

According to Apple, the new Music app, which replaces iTunes, removes support for automatically syncing playlists with third-party apps using XML. 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 seamlessly transmit data between apps.

Catalina’s Music app does support automatic library syncing with other apps, but many DJ apps haven’t been updated yet to support the new method.

Tons of popular DJ apps, like Rekordbox and Traktor, read XML files and relied on iTunes’ syncing feature. Over the years, iTunes became the de facto way for lots of DJs to sort through their massive file libraries and quickly find tracks while performing.

But this means updating to Catalina will replace iTunes with Music, and that, in turn, will break communication between the app and many existing DJ softwares. According to Apple, if a customer is using software that relies on the XML method for syncing, 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.

There is a workaround for getting XML files out of the new Music app, it’s just a little more complicated and not automated. As shown in this video, you manually export the library as an XML file and then load it into your DJ app. The problem with this workaround is that these are static files — you’d have to export a new one every time you want to update a playlist, which is a pain.

Essentially, if you’re a DJ and you have put tons of time into sorting music in your iTunes playlists for whatever software you use, installing Catalina can make all your hard work nearly useless if your preferred app isn’t ready for the update.

Correction October 10th, 5:30PM ET: The new Music app can still export XML files, but it is losing the feature that automatically syncs them with other apps. A statement from Apple initially said XML would not be supported within the app. This story has also been updated to clarify that Music supports a new method for automatically syncing playlists that third-party apps can be updated to support.