Hello Apple Developer Team,
We are observing a BLE connectivity issue in our application BlueDiamond Mobile Elite after upgrading devices to iOS 27 Public Beta.
Environment App: BlueDiamond Mobile Elite Platform: iOS 27 Public Beta Framework: CoreBluetooth Device Type: iPhone BLE Peripheral: Access control/BLE reader Testing Status: BLE scanning works correctly. Reader discovery works correctly. Connection establishment succeeds. Service and characteristic discovery complete successfully. Issue occurs during credential transmission. Problem Description
After connecting to a BLE reader, our application sends mobile credentials to the reader using CoreBluetooth.
The workflow is:
Scan for BLE readers. Discover target reader. Connect to reader. Discover services and characteristics. Start credential transfer. BLE connection disconnects unexpectedly during or immediately after the credential write operation.
The disconnect occurs before the credential transaction completes successfully.
Observed Behavior BLE scanning is functioning normally on iOS 27 Public Beta. The reader is discovered without issues. Connection is established successfully. Credential provisioning/credential write operation triggers the problem. centralManager(_:didDisconnectPeripheral:error:) is invoked after the credential transfer attempt. The credential is not successfully delivered to the reader. Expected Behavior
The BLE connection should remain active throughout the credential provisioning process and disconnect only after the transaction is completed or when explicitly terminated by the application.
Additional Information The same credential issuance flow worked correctly on previous iOS versions. We have already addressed another iOS 27 compatibility issue related to QR code access by updating to Apple's recommended APIs. We are currently investigating whether the BLE disconnection is caused by: Changes in CoreBluetooth behavior in iOS 27 Public Beta. MTU/write packet handling. Write-with-response versus write-without-response behavior. Peripheral firmware compatibility. Credential payload size or transfer timing.
Questions Are there any known CoreBluetooth regressions or behavior changes in iOS 27 Public Beta related to characteristic writes or BLE credential provisioning?
Has anyone observed unexpected peripheral disconnects during write operations on iOS 27 Public Beta?
Are there any recommended changes for applications performing secure credential transfers to BLE peripherals?
Any guidance would be greatly appreciated.