• Android version: 9
• Phone model: Honor COL-L29 (COL-L29RU)
• Briar version: 1.2.4 (75dfa805)

Stacktrace:

java.lang.SecurityException: Not allowed for non-active users
        at android.os.Parcel.createException(Parcel.java:1953)
        at android.os.Parcel.readException(Parcel.java:1921)
        at android.os.Parcel.readException(Parcel.java:1871)
        at android.bluetooth.IBluetoothSocketManager$Stub$Proxy.createSocketChannel(IBluetoothSocketManager.java:207)
        at android.bluetooth.BluetoothSocket.bindListen(BluetoothSocket.java:456)
        at android.bluetooth.BluetoothAdapter.createNewRfcommSocketAndRecord(BluetoothAdapter.java:2152)
        at android.bluetooth.BluetoothAdapter.listenUsingInsecureRfcommWithServiceRecord(BluetoothAdapter.java:2103)
        at org.briarproject.bramble.plugin.bluetooth.AndroidBluetoothPlugin.openServerSocket(AndroidBluetoothPlugin.java:158)
        at org.briarproject.bramble.plugin.bluetooth.AndroidBluetoothPlugin.openServerSocket(AndroidBluetoothPlugin.java:57)
        at org.briarproject.bramble.plugin.bluetooth.BluetoothPlugin.lambda$bind$0$BluetoothPlugin(BluetoothPlugin.java:179)
        at org.briarproject.bramble.plugin.bluetooth.-$$Lambda$BluetoothPlugin$5LFrMRmXQDZNSHk-RYMiHxB1iBE.run(Unknown Source:2)
        at java.util.concurrent.ThreadPoolExecutor.processTask(ThreadPoolExecutor.java:1187)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1152)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
        at java.lang.Thread.run(Thread.java:784)

Edited log:

12-23 13:01:56.423 I/AndroidNetworkManager: Received broadcast android.intent.action.SCREEN_OFF
...
12-23 13:01:57.318 I/AndroidNetworkManager: Received broadcast android.intent.action.SCREEN_ON
...
12-23 13:02:01.460 I/AndroidBluetoothPlugin: Scan mode: None
12-23 13:02:02.034 I/AndroidBluetoothPlugin: Scan mode: None
12-23 13:02:02.051 I/BluetoothPlugin: java.io.IOException: read failed, socket might closed or timeout, read ret: -1
12-23 13:02:02.069 I/BluetoothPlugin: Bluetooth disabled
12-23 13:02:02.070 I/BluetoothConnectionLimiterImpl: All connections closed
...
12-23 13:02:05.087 I/BluetoothPlugin: Bluetooth enabled
12-23 13:02:05.257 I/BluetoothPlugin: Local address null

No activities are shown stopping/starting when the screen turns off/on, which suggests Briar's running in the background. Looks like there might be a restriction on background apps binding Bluetooth sockets.