⚠ It'd be great to get some Apple Dev eyes on this -- it's one of my last remaining issues before submission. Regarding migrating Sign In with Apple users from team PLR8R96VKA to team Y76F338229... I'm following the migration steps at the bottom of https://developer.apple.com/documentation/signinwithapple, in the Transfers Across Teams section. My call to the /auth/usermigrationinfo endpoint results in a 400 error: invalid_request, but my request params all look correct: transfer_sub is set to the the value I got from a successful /auth/usermigrationinfo response. client_id is set to Services ID of the new team's Sign In with Apple service. client_secret was built from the new team's Key ID, Team ID and Services ID. I know it's content and format is valid because it worked fine when calling the /auth/token endpoint. I know my auth token is fine (the one I got from /auth/token)--I'm sure I'd see an auth error if it wasn't. Is there any way I can get more information about what is invalid about the request?

I operate a website that offers Sign In with Apple as an authentication option for users. When I originally set this up a couple years ago, I'd created an App ID using my personal Developer account, along with the appropriate Services ID and Key. I'm now in the process of creating an iOS app offering users similar functionality. But for this, I have a new, business Developer account, where I've created an App ID and all the same ids allowing Sign In with Apple. It feels like the first appropriate thing to do—before starting my iOS sign-in—is to get my existing website users migrated from my personal developer team to my new business developer team. I found that process very well documented by technote TN3159, which describes this as a six-step process in terms of Team A handing a project to Team B. Team A obtains access token(s) Team A generates transfer identifiers Team A initiates app transfer to Team B Team B obtains access token(s) Team B exchanges transfer identifiers Team B confirms successful user migration ✓ I'm successfully able to complete steps 1 and 2. ✘ Step 3 doesn't seem possible, as it looks like that applies to a team transferring a published app to another team. But I figured maybe that didn't matter in my case, as my website uses a Services ID, not an App ID. ✓ I'm successfully able to complete step 4. ✘ But step 5—the important part, where I get the transfer ID—fails with an invalid_request error. I suspect this is because step 3 really was important. But I can't find a way to transfer an app that isn't really an app, just a website using the Sign In with Apple service. Anyway, any help would be greatly appreciated.