Yep I was aware of this but I’m not trying a short name and increasing length of the address doesn’t seem to matter, always gives me the same generic error.

There are a few reports of old Apple IDs preventing the use of that email address OR when the address is used as a recovery email on a different Apple ID. Basically if it’s been known to Apple before it can cause a problem. I’m not sure how you resolve that, but for the record I’m trying to add entirely new addresses that can’t possibly have been used or seen by Apple before so that is not this issue.

I’ve also tried a few different domains and different formats for the bit before the @ and nothing succeeds which leads me to believe it is an account issue rather than related to the domain or address. I suspect something to do with it being an old account that is now on Apple One but was once upgraded from a student account and also moved between countries - something like that meaning I don’t have a particular bit flipped for it to work. I’ve no idea how to test or resolve that though!

Thats good to hear. Do you have a separate App Store account (that probably doesn't have an iCloud email address associated with it), or do you sign into both iCloud and App Store with the one me.com address?

Just tried again and it seems to have worked this time ... I tried last night and it didn't, so they must have deployed an update overnight.

Thanks david-apple - this makes sense now I know it! 🤦‍♂️ Maybe I should have followed the docs more closely ... it has massively simplified my code so I am very happy. Additionally, looking at this I realised that I can do albumRequest.properties = [.tracks] to get the tracks from the first request as I'll always need them in my use case, removing the need for the detailedAlbum. 👌