Hello Knuppel,

It looks like the issue is not with bluetooth but with the UI (KetaiList).  That UI element must be different from the 2.3 version.  Try connecting to the bluetooth device manually.  Try the following:

Through the android bluetooth utility scan for the device to get the name of it.
Use that name directly to connect to the device instead of using the list to pick the device.

so get rid of the KetaiList and connect directly using the following:

String selection = "ARDUINO_BLUETOOTH_NAME";  // REPLACE with the bluetooth name of your shield
bt.connectToDeviceByName(selection);

you could trigger it via a mousepressed or a keypressed.

That should bypass the error you're seeing and bluetooth may just work on 2.3.x.

Let me know if you have any luck!

thanks,

j