I'm currently using the SerialPort connection type in twisted 15.5.0 with python 2.7.7 on a windows machine. Twisted serial communications with the serial port fail when pyserial is upgraded from 2.7 to 3.0.1 and fails with the following error. Traceback (most recent call last): File "C:\Anaconda\Scripts\fmv3dbg-script.py", line 9, in <module> load_entry_point('fmv3tools==0.2.5', 'console_scripts', 'fmv3dbg')() File "C:\Anaconda\lib\site-packages\fmv3tools-0.2.5-py2.7.egg\fmv3tools\fmv3dbg.py", line 338, in main server = create_system(args) File "C:\Anaconda\lib\site-packages\fmv3tools-0.2.5-py2.7.egg\fmv3tools\fmv3dbg.py", line 310, in create_system server = SerialServer(com_port, outputs=outputs) File "C:\Anaconda\lib\site-packages\fmv3tools-0.2.5-py2.7.egg\fmv3tools\fmv3dbg.py", line 57, in __init__ FMv3SerialGateway.__init__(self, com_port, *args, **kwargs) File "C:\Anaconda\lib\site-packages\flatmesh-0.2.8-py2.7.egg\flatmesh\fmv3_datacoms.py", line 403, in __init __ baudrate=baudrate) File "C:\Anaconda\lib\site-packages\twisted-15.5.0-py2.7-win32.egg\twisted\internet\_win32serialport.py", line 56, in __init__ self._finishPortSetup() File "C:\Anaconda\lib\site-packages\twisted-15.5.0-py2.7-win32.egg\twisted\internet\_win32serialport.py", line 65, in _finishPortSetup flags, comstat = win32file.ClearCommError(self._serial.hComPort) AttributeError: 'Serial' object has no attribute 'hComPort' I've removed pyserial 3.0.1 from my system for the moment but I was wondering if there is a way to have both pyserial 2.7 and 3.0.1 on my system when using twisted? Thanks, Chris