RepHost/Ubuntu serial error

System.IO.IOException: Input/output error
  at System.IO.Ports.SerialPortStream.ThrowIOException () [0x00000] in <filename unknown>:0
  at System.IO.Ports.SerialPortStream.get_BytesToRead () [0x00000] in <filename unknown>:0
  at System.IO.Ports.SerialPort.get_BytesToRead () [0x00000] in <filename unknown>:0
  at (wrapper remoting-invoke-with-check) System.IO.Ports.SerialPort:get_BytesToRead ()
  at RepetierHost.model.PrinterConnection.ReadThread () [0x00000] in <filename unknown>:0