[winswitch] Why can't I start xpra on a remote host and connect to it?

[Tim]

Hi,I use the following commands to start xpra server on a remote host and connect to it.But half of time it doesn't work, while sometimes it works.The first command is to kill any remote xpra server process if any. it seems to increase the chance of working a bit, but not always.
Thanks.

    $ ssh "olive" killall xpra 
    $ xpra shadow ssh:olive:0
    sh: 0: getcwd() failed: Input/output error
    2019-11-26 17:52:33,854 Xpra gtk2 client version 2.1.3-r17247M 64-bit
    2019-11-26 17:52:33,854  running on Linux Ubuntu 18.04 bionic
    sh: 0: getcwd() failed: Input/output error
    2019-11-26 17:52:36,757 GStreamer version 1.14.5 for Python 2.7.15 64-bit
    2019-11-26 17:52:38,389 Warning: vendor 'Intel Open Source Technology Center' is greylisted,
    2019-11-26 17:52:38,390  you may want to turn off OpenGL if you encounter bugs
    2019-11-26 17:52:38,411 PyOpenGL warning: missing accelerate module
    2019-11-26 17:52:38,486 OpenGL enabled with Mesa DRI Mobile Intel® GM45 Express Chipset
    2019-11-26 17:52:38,570  keyboard settings: rules=evdev, model=pc105, layout=us
    2019-11-26 17:52:38,575  desktop size is 1440x900 with 1 screen:
    2019-11-26 17:52:38,575   :0.0 (381x238 mm - DPI: 96x96) workarea: 1440x876
    2019-11-26 17:52:38,576     monitor 1 (303x190 mm - DPI: 120x120)
    2019-11-26 17:52:39,266 Error: cannot watch for video device changes without pyinotify:
    2019-11-26 17:52:39,267  No module named pyinotify
    Warning: cannot use the system proxy for 'shadow' subcommand,
     failed to connect to '/run/xpra/system':
     [Errno 2] No such file or directory
    Entering daemon mode; any further errors will be reported to:
      /run/user/1000/xpra/:0.log
    InitException: failed to identify the new server display!
    xpra initialization error:
     failed to identify the new server display!
    2019-11-26 17:52:59,270 Error: failed to receive anything, not an xpra server?
    2019-11-26 17:52:59,270   could also be the wrong protocol, username, password or port
    2019-11-26 17:52:59,270 Connection lost
    2019-11-26 17:52:59,273 Error: printing disabled:
    2019-11-26 17:52:59,273  No module named cups