I am not able to use Feedback because the app can not reset my password.

We are integrating Sign in with Apple for our web application and have been stuck on an invalid_client error during the token exchange step. The Problem The authorization step works fine — the user authenticates on Apple's page and a valid authorization code is returned to our callback URL. However, when we exchange that code at https://appleid.apple.com/auth/token, it returns: {"error": "invalid_client"} The Puzzling Part When we send a dummy/expired authorization code with the exact same client_id and client_secret, Apple returns: {"error": "invalid_grant", "error_description": "The code has expired or has been revoked."} This confirms that our client credentials (client_id + client_secret JWT) are valid and accepted by Apple. The invalid_client error only occurs when a real, freshly-issued authorization code is used. Configuration Service ID configured with Sign in with Apple enabled Primary App ID with Sign in with Apple capability enabled Domain verified, Return URL registered Key created with Sign in with Apple enabled, linked to the correct Primary App ID Client Secret JWT Generated per Apple's documentation: Header: alg: ES256, kid set to our Key ID Claims: iss: Team ID iat: current timestamp exp: iat + 6 months (within Apple's limit) aud: https://appleid.apple.com sub: Service ID (matches the client_id used in authorization) Signed with: the .p8 private key associated with the Key Token Exchange Request POST https://appleid.apple.com/auth/tokenContent-Type: application/x-www-form-urlencodedclient_id=client_secret=code=grant_type=authorization_coderedirect_uri= What We've Tried Standalone test endpoint — built a minimal endpoint (no framework) that does the token exchange via server-side curl. Same invalid_client. Multiple Service IDs — created and tried 3 different Service IDs. All produce the same error with real codes. Multiple Keys — tried 2 different keys. Same error. Verified redirect_uri matches exactly between the authorization request and token request. Verified client_id matches exactly between the authorization URL and token request. Used client_secret_post (credentials in body, not Basic auth header). Freshness — code is used immediately upon receipt (within seconds), well before the 5-minute expiry. Filed a Developer Support case — was directed to Forums. Summary Scenario code Result Dummy/expired code abc123 invalid_grant (credentials accepted) Real fresh code from Apple callback invalid_client This pattern suggests something goes wrong specifically when Apple validates the authorization code against the client — even though the client credentials themselves are accepted in isolation. Has anyone encountered this behavior? Is there a known configuration issue that could cause invalid_client only with valid authorization codes? Any guidance would be greatly appreciated.

Hello everyone, We are currently preparing for an App Transfer to a new Apple Developer account due to a corporate merger. We are trying to figure out the best way to handle Apple Sign-In user migration and would love to get some advice on our proposed fallback plan. 📌 Current Situation We need to transfer our app's ownership to a new corporate entity. The app heavily relies on Apple Sign-In. The Issue: We did not collect the transfer_sub values during our initial development phase. Although we started collecting them recently, we will not have them for all existing users by the time the transfer happens. 🚨 The Risk (The 60-Day Rule) Based on Apple's documentation, even if we provide the transfer_sub, users must log into the app within 60 days of the transfer to successfully migrate their accounts. This means that users who log in after 60 days, or those whose transfer_sub is missing, will fail the Apple migration process. They will be treated as "new users" and will lose access to their existing account data. 💡 Our Proposed Custom Recovery Flow Since we cannot rely entirely on Apple's automated migration, we are planning to build a custom internal account recovery process to prevent user drop-off: A user (who failed the migration or logged in after 60 days) attempts to use Apple Sign-In on the transferred app. Since the existing account isn't linked, Apple generates a new identifier (sub), and the user enters the new sign-up flow. During the sign-up process, we enforce a mandatory identity verification step (e.g., SMS phone number verification). We query our existing user database using this verified information. If a matching existing user is found: We interrupt the sign-up process and display a prompt: "An existing account was found. We will link your account." We then update our database by mapping the new Apple sub value to their existing account record, allowing them to log in seamlessly. ❓ My Questions App Review Risk: Could this manual mapping approach—overwriting the Apple sub on an existing account based on internal identity verification—violate any Apple guidelines or result in an App Store rejection? Shared Experiences: Has anyone dealt with missing transfer_sub values or the 60-day migration limit during an App Transfer? How did you mitigate user loss? Best Practices: Are there any alternative, safer, or more recommended workarounds for this scenario?