java.lang.NullPointerException: Attempt to invoke virtual method 'java.util.UUID android.bluetooth.BluetoothGattCharacteristic.getUuid()' on a null object reference at edu.mit.appinventor.ble.BluetoothLEint$BLEOperation.registerPendingOperation(BluetoothLEint.java:257) at edu.mit.appinventor.ble.BluetoothLEint$BLEReadOperation.subscribe(BluetoothLEint.java:356) at edu.mit.appinventor.ble.BluetoothLEint$BLEReadOperation.run(BluetoothLEint.java:325) at android.os.Handler.handleCallback(Handler.java:997) at android.os.Handler.dispatchMessage(Handler.java:111) at android.os.Looper.loopOnce(Looper.java:237) at android.os.Looper.loop(Looper.java:325) at android.app.ActivityThread.main(ActivityThread.java:10378) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:635) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:961)
Note: You will not see another error reported for 5 seconds.