We did an app transfer in mid-August as part of our process to incorporate the business. We have approximately 100,000 users who have logged in with their Apple IDs, and as part of the transfer process, we followed the documentation below to transfer the account information. https://developer.apple.com/documentation/sign_in_with_apple/bringing_new_apps_and_users_into_your_team During the identifier exchange process, an invalid_request error occurred for approximately 10,000 users. https://developer.apple.com/documentation/sign_in_with_apple/bringing_new_apps_and_users_into_your_team#3559300 We successfully transferred the remaining users using the same script and procedure. Even when repeated multiple times, the error consistently occurs with the same users. Based on this situation, we believe that the error may be caused by user-related factor. Specifically, we would like to understand the potential causes of request errors other than the reasons listed below. The only user-related cause, ‘The user has revoked authorization for the client,’ is not relevant to this case, as it pertains to an error when issuing the transfer identifier. (not exchanging) https://developer.apple.com/documentation/technotes/tn3107-resolving-sign-in-with-apple-response-errors#Possible-reasons-for-invalid-request-errors Details of the request content are documented in FB14898615. Although we submitted feedback from the account after the transfer, we have not received a response for over a week, so we are reaching out here as well. [Similar problem] https://developer.apple.com/forums/thread/761968