BLE connection failed with REASON_TIMEOUT(10)

[Hu-Muran]

Dear developers,

When using this library, we occasionally encounter the REASON_TIMEOUT issue, which causes connection failures and leads to user complaints. Could you please explain the specific cause of this problem? Is it related to the Bluetooth function of the Android system? When REASON_TIMEOUT occurs, is the Bluetooth disconnection triggered by the App?

09-19 13:04:39.822 D [Nordic] VMStack (BCManagerHandlerThread) [Callback] Connection state changed with status: 0 and new state: 0 (DISCONNECTED) - device = [address = 4E:9F:93:04:xx:xx, name = null, uuids = null]
09-19 13:04:39.833 D [Nordic] VMStack (BCManagerHandlerThread) Disconnected - device = [address = 4E:9F:93:04:xx:xx, name = null, uuids = null]
09-19 13:04:39.843 D [Nordic] VMStack (BCManagerHandlerThread) gatt.close() - device = [address = 4E:9F:93:04:xx:xx, name = null, uuids = null]
09-19 13:04:39.869 I [XXX] BluetoothClient (BCManagerHandlerThread) connectionObserver.onDeviceDisconnected(): device = [address = 4E:9F:93:04:xx:xx, name = null, uuids = null], reason = REASON_TIMEOUT(10)

[philips77]

Hi,
Seems like the REASON_TIMEOUT is thrown here:

Android-BLE-Library/ble/src/main/java/no/nordicsemi/android/ble/BleManagerHandler.java

Line 2321 in 565d0e1

notifyDeviceDisconnected(gatt.getDevice(), mapDisconnectStatusToReason(status));

This occurs when the device disconnects without the user calling disconnect(). Some devices report status=8 (timeout), but some 0 (success):

Android-BLE-Library/ble/src/main/java/no/nordicsemi/android/ble/BleManagerHandler.java

Lines 3038 to 3042 in 565d0e1

	// When a remote device disconnects, some phones return the TIMEOUT error, while other
	// just SUCCESS. Anyway, in both cases the device has not been disconnected by the
	// user, so the reason should be the TIMEOUT.
	case GattError.GATT_CONN_TIMEOUT, GattError.GATT_SUCCESS ->
	ConnectionObserver.REASON_TIMEOUT;

Anyway, only based on your attached logs I would say, that the link terminates for some reason (out of range? phone's issue? device restarts?) and this is reported to the app (library) as disconnection with status 0.

[Hu-Muran]

Hi philips, thank you very much for your quick response.

So we cannot identify the exact cause of the Bluetooth disconnection. At the very least, the disconnection is not triggered at the App or SDK level. Does that make sense?