[winswitch] Unable to start - "unknown format for display name"

[Nikolaus Rath]

Hi,

I'm trying to use xpra for the first time on two new systems, but it 
gives me an error that I haven't seen before:

$ xpra start ssh:niratiquity.fra.corp.google.com --start=xfce4-terminal
2017-12-13 12:14:09,386 Xpra gtk2 client version 0.17.6-r14322
2017-12-13 12:14:09,386  running on Linux Debian rodete rodete
2017-12-13 12:14:09,386 Warning: failed to import opencv:
2017-12-13 12:14:09,386  No module named cv2
2017-12-13 12:14:09,387  webcam forwarding is disabled
2017-12-13 12:14:09,567 GStreamer version 1.12 for Python 2.7
2017-12-13 12:14:09,912 PyOpenGL warning: missing accelerate module
2017-12-13 12:14:09,914 OpenGL enabled with Quadro K1200/PCIe/SSE2
2017-12-13 12:14:09,998  detected keyboard: rules=evdev, model=pc105, 
layout=us
2017-12-13 12:14:09,999  desktop size is 4000x2560 with 1 screen:
2017-12-13 12:14:09,999   :0.0 (1058x677 mm - DPI: 96x96)
2017-12-13 12:14:09,999     monitor 1 2560x1440 at 0x438 (597x336 mm - 
DPI: 108x108)
2017-12-13 12:14:09,999     monitor 2 1440x2560 at 2560x0 (597x336 mm - 
DPI: 61x193)
2017-12-13 12:14:09,999  upscaled by 167%, virtual screen size: 2400x1536
2017-12-13 12:14:10,000   :0.0 (1058x677 mm - DPI: 57x57)
2017-12-13 12:14:10,000     monitor 1 1536x864 at 0x263 (597x336 mm - 
DPI: 65x65)
2017-12-13 12:14:10,000     monitor 2 864x1536 at 1536x0 (597x336 mm - 
DPI: 36x116)
Entering daemon mode; any further errors will be reported to:
   /home/nikolausr/.xpra/S7666.log
Actual log file name is now: /home/nikolausr/.xpra/:0.log
2017-12-13 12:14:33,060 xpra initialization error:
2017-12-13 12:14:33,060  unknown format for display name: S7663
2017-12-13 12:14:33,060
2017-12-13 12:14:33,062 Error: printing disabled:
2017-12-13 12:14:33,063  No module named cups
2017-12-13 12:14:33,069 Connection lost

The logs on the remote system don't show anything suspicious either:

$ cat /home/nikolausr/.xpra/:0.log
Failed to rename log file "/home/nikolausr/.xpra/Xorg.S7666.log" to 
"/home/nikolausr/.xpra/Xorg.S7666.log": No such file or directory

X.Org X Server 1.19.3
Release Date: 2017-03-15
[...]
Using display number provided by /usr/lib/xorg/Xorg: :0
failed to rename Xorg log file from 
'/home/nikolausr/.xpra/Xorg.S7666.log' to 
'/home/nikolausr/.xpra/Xorg.:0.log'
  [Errno 2] No such file or directory
2017-12-13 13:14:18,304 created unix domain socket: 
/home/nikolausr/.xpra/niratiquity.fra.corp.google.com-0
2017-12-13 13:14:18,733 Pillow error saving jpeg with quality=50, 
speed=50, alpha=True
2017-12-13 13:14:18,733  cannot write mode RGBA as JPEG
Traceback (most recent call last):
   File "/usr/lib/python2.7/dist-packages/xpra/codecs/pillow/encode.py", 
line 157, in selftest
     v = encode(encoding, img, q, s, alpha)
   File "/usr/lib/python2.7/dist-packages/xpra/codecs/pillow/encode.py", 
line 89, in encode
     im.save(buf, coding.upper(), **kwargs)
   File "/usr/lib/python2.7/dist-packages/PIL/Image.py", line 1893, in save
     save_handler(self, fp, filename)
   File "/usr/lib/python2.7/dist-packages/PIL/JpegImagePlugin.py", line 
604, in _save
     raise IOError("cannot write mode %s as JPEG" % im.mode)
IOError: cannot write mode RGBA as JPEG
2017-12-13 13:14:18,835 Warning: failed to load the mdns avahi publisher:
2017-12-13 13:14:18,836  No module named avahi
2017-12-13 13:14:18,836  either fix your installation or use the 
'mdns=no' option
2017-12-13 13:14:19,243 Warning: webcam forwarding is disabled
2017-12-13 13:14:19,243  the virtual video directory 
'/sys/devices/virtual/video4linux' was not found
2017-12-13 13:14:19,243  make sure that the 'v4l2loopback' kernel module 
is installed and loaded
2017-12-13 13:14:19,243 found 0 virtual video devices
2017-12-13 13:14:19,257 pulseaudio server started with pid 7702
2017-12-13 13:14:19,470 GStreamer version 1.12 for Python 2.7

Someone able to help?


Best,
-Nikolaus