When the client connects to the server, there are port forwarding and application startup errors.

[II] 2018/13/04 09:38:53.375532 ConchConnection.forward_port(12497,127.0.0.1,24065)
[II] 2018/13/04 09:39:31.742001 WinSwitchApplet.do_start_session(ServerConfig(desktop:158515233878749),Command(Mousepad: mousepad %F),xpra,None,{},False)
[II] 2018/13/04 09:39:31.742075 WinSwitchApplet.attention(Starting Mousepad,None)
[II] 2018/13/04 09:39:31.742134 StatusIconTray.animate_status_icon(Starting Mousepad,5) now=1523601571.74, tray_widget_animate_until=1523601505.56
[II] 2018/13/04 09:39:31.908503 ServerLink.add_port_forward(None,127.0.0.1,15071) adding new port forward
[II] 2018/13/04 09:39:31.908637 ConchConnection.forward_port(12498,127.0.0.1,15071)
[II] 2018/13/04 09:39:35.937471 ServerLineConnection.do_message(9e007000aad84b759b6f03735717ba4d,Session Mousepad Failed,Session failed to start,)
[II] 2018/13/04 09:39:54.238773 UI_Util.get_command_menu_entry(ServerConfig(desktop:158515233878749),Command(Gscriptor: gscriptor)) missing icon!
[II] 2018/13/04 09:39:54.239043 UI_Util.get_command_menu_entry(ServerConfig(desktop:158515233878749),Command(Jaxx: "/home/username/cryptowallets/jaxx-1.3.13-x86_64.AppImage" %U)) missing icon!
[II] 2018/13/04 09:39:54.240210 UI_Util.get_command_menu_entry(ServerConfig(desktop:158515233878749),Command(TurboVNC Viewer: /opt/TurboVNC/bin/vncviewer)) missing icon!
[II] 2018/13/04 09:39:54.241673 UI_Util.get_command_menu_entry(ServerConfig(desktop:158515233878749),Command(OpenCity: opencity)) missing icon!
[II] 2018/13/04 09:39:54.247141 UI_Util.get_command_menu_entry(ServerConfig(desktop:158515233878749),Command(aMule: amule %u)) missing icon!
[II] 2018/13/04 09:39:54.251555 UI_Util.get_command_menu_entry(ServerConfig(desktop:158515233878749),Command(Power Manager: xfce4-power-manager-settings)) missing icon!
[II] 2018/13/04 09:39:54.252573 UI_Util.get_command_menu_entry(ServerConfig(desktop:158515233878749),Command(TeXdoctk: texdoctk)) missing icon!
[II] 2018/13/04 09:39:54.253640 UI_Util.get_command_menu_entry(ServerConfig(desktop:158515233878749),Command(PyCrust: pycrust)) missing icon!
[II] 2018/13/04 09:39:54.255005 UI_Util.get_command_menu_entry(ServerConfig(desktop:158515233878749),Command(LMMS: env QT_X11_NO_NATIVE_MENUBAR=1 lmms %f)) missing icon!
[II] 2018/13/04 09:39:54.257128 UI_Util.get_command_menu_entry(ServerConfig(desktop:158515233878749),Command(GAdmin-Rsync: su-to-root -X -c /usr/sbin/gadmin-rsync)) missing icon!
[II] 2018/13/04 09:39:54.257361 UI_Util.get_command_menu_entry(ServerConfig(desktop:158515233878749),Command(GSmartControl: "/usr/bin/gsmartcontrol-root")) missing icon!
[II] 2018/13/04 09:39:54.259273 UI_Util.get_command_menu_entry(ServerConfig(desktop:158515233878749),Command(UNetbootin: /usr/bin/unetbootin)) missing icon!
[II] 2018/13/04 09:39:54.287996 WinSwitchApplet.do_start_session(ServerConfig(desktop:158515233878749),Desktop(Xfce Session: startxfce4),vnc,None,{},False)
[II] 2018/13/04 09:39:54.288073 WinSwitchApplet.attention(Starting Xfce Session,None)
[II] 2018/13/04 09:39:54.288128 StatusIconTray.animate_status_icon(Starting Xfce Session,5) now=1523601594.29, tray_widget_animate_until=1523601576.74
[II] 2018/13/04 09:39:54.547923 ServerLink.add_port_forward(None,127.0.0.1,16072) adding new port forward
[II] 2018/13/04 09:39:54.548147 ConchConnection.forward_port(12499,127.0.0.1,16072)
[II] 2018/13/04 09:39:55.599431 ProtocolHandler.do_encrypted_command(78296cadaa664db4903f9daf30f421f5e745774aa2ab268880acc074aa64e8b4be461c80a2b4e9d6cb5be604d2dc6d8d7...) decrypted command=send_session '4011ea7ccbbf4b4caa82f47d86bb0b98','9e007000aad84b759b6f03735717ba4d','base64:N2UyNGMwMmE= '
[II] 2018/13/04 09:39:55.599610 VNCClientUtil.attach(ServerConfig(desktop:158515233878749),ClientSession(:71 - vnc - connecting),127.0.0.1,12499)
[II] 2018/13/04 09:39:55.625427 VNCClientUtil.do_real_attach(ServerConfig(desktop:158515233878749),ClientSession(:71 - vnc - connecting),127.0.0.1,12499) saved password '#######' in /home/username/.winswitch/client/sessions/4011ea7ccbbf4b4caa82f47d86bb0b98/session.pass
[II] 2018/13/04 09:39:55.625532 VNCClientUtil.exec_client(ServerConfig(desktop:158515233878749),ClientSession(:71 - vnc - connecting),['/usr/bin/vncviewer', 'PasswordFile=/home/username/.winswitch/client/sessions/4011ea7ccbbf4b4caa82f47d86bb0b98/session.pass', 'name=Xfce Session on desktop', '127.0.0.1::12499'],None,None,available,True) starting SimpleLineProcess
[II] 2018/13/04 09:39:55.634440 VNCClientUtil.started(<winswitch.util.process_util.SimpleLineProcess instance at 0x7f5abbdf4dd0>) pid=None
[II] 2018/13/04 09:39:55.634966 SimpleLineProcess.start() process(['/usr/bin/vncviewer', 'PasswordFile=/home/username/.winswitch/client/sessions/4011ea7ccbbf4b4caa82f47d86bb0b98/session.pass', 'name=Xfce Session on desktop', '127.0.0.1::12499'])=<Process pid=6419 status=-1>
[II] 2018/13/04 09:39:56.214816 PortForwardChannel.__init__(<winswitch.net.conch_util.ConchConnection instance at 0x7f5ac06b5b48>,<function forwarding_ready at 0x7f5abbdd7578>,<function forwarding_failed at 0x7f5abbdd7aa0>)
[II] 2018/13/04 09:39:56.214968 ConchConnection.openChannel(<winswitch.net.conch_util.PortForwardChannel instance at 0x7f5abbdf4758>,'\x00\x00\x00\t127.0.0.1\x00\x00>\xc8\x00\x00\x00\t127.0.0.1\x00\x00\xcf\xde')
[II] 2018/13/04 09:39:56.215638 VNCClientUtil.handle_line_connected(ClientSession(:71 - vnc - connecting), CConn:       connected to host 127.0.0.1 port 12499) ServerConfig(desktop:158515233878749)
[II] 2018/13/04 09:39:56.215699 WinSwitchApplet.update_session_status(ServerConfig(desktop:158515233878749),ClientSession(:71 - vnc - connecting),connected)
[II] 2018/13/04 09:39:56.243185 ServerLink.forwarding_ready()

In trying to get a WinSwitch/xpra server on Ubuntu to work with a WinSwitch/xpra client on OSX, I had to fight with xmodmap a bit (need to use Alt for Eclipse, emacs, etc.). I found the check for running X server not to be quite right. The following diff is for an older version of winswitch/client/client_base.py (I can't use the latest due to ​https://xpra.org/trac/ticket/92), so the lines aren't current but their content hasn't changed.

The first change fixes the search of lines for "org.x.startx". In the old form, line.find returns -1 for any line without a match, triggering on the very first line ("PID Status Label"). Python documentation states a preference for "substring in string", when the position of substring in string is not needed. If you want to insist on "org.x.startx" at the very end of the line, the test could be: if line.endswith("org.x.startx"):

The second change corrects the check for a process that's running now ("0" in parts[1] appears to indicate that the process has terminated and returned 0). Checking that parts[0] is NOT "-" is a valid check for a running process, as well. The man pages are a bit vague.

The changes below work on my MacBookPros at home and at work with 10.5 and 10.6:

432c432
<                                       if line.find("org.x.startx$"):
---
>                                       if "org.x.startx" in line:
436c436
<                                                       started = parts[1]=="0"
---
>                                                       started = parts[1]=="-"

I hope this helps. -Alexey

This was mentioned in #198 but it seems like it was overlooked.

NXAGENT - Version 3.5.0

Copyright (C) 2001, 2011 NoMachine.
See http://www.nomachine.com/ for more information.

Info: Agent running with pid '8227'.
Session: Starting session at 'Wed Oct  3 00:44:12 2012'.
Error: Aborting session with 'Unable to open display 'nx/nx,options=/home/me/.winswitch/server/sessions/72/nx_options.txt:72''.
Session: Aborting session at 'Wed Oct  3 00:44:12 2012'.
Session: Session aborted at 'Wed Oct  3 00:44:12 2012'.

Why is all that extra stuff being sent to NX for the display, instead of it just being ":72"?

winswitch:
  Installed: 0.12.16-4
  Candidate: 0.12.16-4
  Version table:
 *** 0.12.16-4 0
        500 http://winswitch.org/ precise/main i386 Packages
        100 /var/lib/dpkg/status