Ok, so it's not just me! So Apple went from an incredibly complicated authentication mechanism for MusicKit that presumably hardly anyone used, to a ridiculously simple one that doesn't work and provides no details as to the cause of the problem.

I started to fill out the feedback, but the sysdiagnose tarball is 540MB! It seems too large to attach to the feedback ticket. Is there a way to reduce the size of the sysdiagnose report? What specifically do you think would be useful to diagnose this issue?

Done, the feedback report is here: https://feedbackassistant.apple.com/feedback/9168339

Ah, I figured that limitation was for playing music, not simply hitting the REST endpoint to query songs. Yes, an improved error message would be helpful.

Thanks. Yeah, the errors are brutal. And if the user doesn't have an active Apple Music subscription (say on a new device), it also fails with .userTokenRequestFailed but .userNotSignedIn would be more accurate. DataRequesting] Failed retrieving MusicKit tokens: Error Domain=ICErrorDomain Code=-8102 "Failed to fetch user token." UserInfo={NSDebugDescription=Failed to fetch user token., NSUnderlyingError=0x2815ba010 {Error Domain=ICErrorDomain Code=-7401 "No active account." UserInfo={NSDebugDescription=No active account.}}}. Throwing .userTokenRequestFailed.

How are we supposed to test that offer codes work? If we use actual apple ids, then you can only test the redemption once per apple id as the subscription is purchased. Does Apple recommend that developers have multiple phone numbers and multiple credit cards to create multiple app store accounts?