Hello @Paris X Pinkney, We're seeing the same Sign in with Apple issue with our app Fitnesta and wanted to add our case here. Team ID: 89Q73MZFUD (BHEEMA NETWORK) Bundle ID / Client ID: com.fitnesta.app Build: 17 (development-signed) Device: iPhone 14 Pro Max, iOS 27.0 Feedback Assistant: FB25156895 Developer Support case: 102993948886 The native Sign in with Apple sheet opens, Face ID succeeds, and then it shows "Sign-Up Not Completed". No authorization or identity token is returned, and nothing reaches our backend. We captured the failure with AuthKit logging on October 11. Apple's server response was: ec = "-24000"; em = "Invalid client."; ptxid = "054f4730-7b92-4b0b-bd07-681037d4378a"; We also ran a control test using Notion on the exact same iPhone and Apple Account, just 19 seconds before reproducing the Fitnesta failure. Notion completed Sign in with Apple successfully (ec = 0), while Fitnesta received Invalid client. Interestingly, AKSQLError -6003 appeared in both the successful Notion flow and our failed flow, so the actual server response seems to be the important difference. We've verified that our App ID is configured as a primary App ID with Sign in with Apple enabled. The signed app and provisioning profile also contain the correct [Default] entitlement. Our developer membership was previously converted from an individual to an organization account, in case that's relevant. We've already submitted Feedback Assistant report FB25156895 with an iOS sysdiagnose and opened Developer Support case 102993948886. Happy to provide the sanitized AuthKit logs privately or retest the same build if needed. Thanks!