io.netty.handler.codec.DecoderException: io.netty.util.IllegalReferenceCountException: refCnt: 0 at app//io.netty.handler.codec.ByteToMessageDecoder.callDecode ...
Can you post debug.log then? (Use https://mclo.gs/ if possible) There might be more info around this line [13:08:54] [Netty Client IO #2/ERROR]: NetworkDispatcher exception ...