Please help addressing the problem of "Error spawning child 'no'"

[pfmiles]

the server.log is shown above,
I was running a simplest 'xterm' program using xpra 5.0.8, in a docker container of debian bullseye system.
The log looked OK at the beginning as the program starts.
But as soon as there's a 'sound' ought to be captured(may be a 'beep' triggered by xterm), the server.log outputs this error:

2024-05-13 19:35:40,884 Error spawning child 'no'
2024-05-13 19:35:40,884  [Errno 2] No such file or directory: 'no'

The sound capture also stopped after this error.
I've never heard of any command line tool named 'no', so I've no idea how to fix this problem.
Does anyone know what's going on here?
Thanks!

[totaam]

You have not included your command line, so it is impossible to tell you what is wrong with it.
For sure, something.

BTW, if you are running in a container, you should be able to choose a better platform than Debian: https://github.com/Xpra-org/xpra/wiki/Platforms

[pfmiles]

Sorry I do pasted a command line output screenshot, but it seems that's a 'private image'.
here's the textual version of it:

admin@0135394f4388:~$ cat /tmp/xpra/100/server.log
2024-05-13 19:33:18,963 created tcp socket '0.0.0.0:10000'
Socket path '/tmp/.X11-unix/X100' not found
2024-05-13 19:33:18,967 no uinput module (not usually needed)
_XSERVTransmkdir: ERROR: euid != 0,directory /tmp/.X11-unix will not be created.
2024-05-13 19:33:20,498 pointer device emulation using XTest
2024-05-13 19:33:20,559 serving html content from '/usr/share/xpra/www'
2024-05-13 19:33:20,559 wrote pid 337 to '/tmp/xpra/100/server.pid'
2024-05-13 19:33:20,591 Warning: socket directory '/tmp/xpra'
2024-05-13 19:33:20,591  expected permissions 700 but found 755
2024-05-13 19:33:20,591 Warning: socket directory '/run/xpra'
2024-05-13 19:33:20,591  expected permissions 775 but found 755
2024-05-13 19:33:20,591 Warning: socket directory '/tmp/xpra/100'
2024-05-13 19:33:20,591  expected permissions 700 but found 750
2024-05-13 19:33:20,592 created unix domain socket '/tmp/xpra/0135394f4388-100'
2024-05-13 19:33:20,592 created unix domain socket '/run/xpra/0135394f4388-100'
2024-05-13 19:33:20,592 created unix domain socket '/home/admin/.xpra/0135394f4388-100'
2024-05-13 19:33:20,592 created unix domain socket '/tmp/xpra/100/socket'
2024-05-13 19:33:20,593 xvfb pid=341
2024-05-13 19:33:20,646 D-Bus notification forwarding is available
2024-05-13 19:33:20,665 pulseaudio server started with pid 383
2024-05-13 19:33:20,665  private server socket path:
2024-05-13 19:33:20,665  '/tmp/xpra/100/pulse/pulse/native'
W: [pulseaudio] authkey.c: Failed to open cookie file '/home/admin/.config/pulse/cookie': No such file or directory
W: [pulseaudio] authkey.c: Failed to load authentication key '/home/admin/.config/pulse/cookie': No such file or directory
W: [pulseaudio] authkey.c: Failed to open cookie file '/home/admin/.pulse-cookie': No such file or directory
W: [pulseaudio] authkey.c: Failed to load authentication key '/home/admin/.pulse-cookie': No such file or directory
2024-05-13 19:33:20,719 watching for applications menu changes in:
2024-05-13 19:33:20,720  '/usr/share/applications'
2024-05-13 19:33:20,758 Warning: lpinfo command failed and returned 1
2024-05-13 19:33:20,758  command used: '/usr/sbin/lpinfo --make-and-model Generic PDF Printer -m'
2024-05-13 19:33:20,770 Warning: lpinfo command failed and returned 1
2024-05-13 19:33:20,770  command used: '/usr/sbin/lpinfo --make-and-model Generic PostScript Printer -m'
2024-05-13 19:33:20,772 Warning: no printer definitions found,
2024-05-13 19:33:20,772  cannot enable printer forwarding
2024-05-13 19:33:20,779 Error parsing xdg menu data:
2024-05-13 19:33:20,779  ParsingError in file '/etc/xdg/menus/debian-menu.menu', File not found
2024-05-13 19:33:20,779  this is either a bug in python-xdg,
2024-05-13 19:33:20,779  or an invalid system menu configuration
2024-05-13 19:33:20,779  for more information, please see:
2024-05-13 19:33:20,779  https://github.com/Xpra-org/xpra/issues/2174
2024-05-13 19:33:20,945 xpra is ready.
2024-05-13 19:33:21,035 some GStreamer elements are missing or unavailable on this system:
2024-05-13 19:33:21,035  vaapih264enc, vaapih265enc, amfh264enc, amfh265enc, x264enc, av1enc
2024-05-13 19:33:21,083 GStreamer version 1.18.4
2024-05-13 19:33:21,122 7.5GB of system memory
2024-05-13 19:33:21,770 OpenGL is supported on display ':100'
2024-05-13 19:33:21,770  using 'llvmpipe (LLVM 11.0.1, 256 bits)' renderer
2024-05-13 19:33:21,777 started command `xterm` with pid 447
2024-05-13 19:33:21,785 started command `ibus-daemon` with pid 448
xterm: cannot load font "-misc-fixed-medium-r-semicondensed--13-120-75-75-c-60-iso10646-1"
2024-05-13 19:33:27,066 python-zeroconf: '::' IPv6 loopback address is not supported
2024-05-13 19:33:28,677 xpra X11 seamless server version 5.0.8-r0
2024-05-13 19:33:28,678  uid=1000 (admin), gid=1000 (admin)
2024-05-13 19:33:28,678  running with pid 337 on Linux Debian 11 bullseye
2024-05-13 19:33:28,679  connected to X11 display :100 with 24 bit colors
2024-05-13 19:35:40,235 Handshake complete; enabling connection
2024-05-13 19:35:40,266 HTML5 Mac OSX Chrome client version 12.0
2024-05-13 19:35:40,270 setting keyboard layout to 'cn'
2024-05-13 19:35:40,341  client root window size is 2560x1205
2024-05-13 19:35:40,342   HTML (677x319 mm - DPI: 96x96)
2024-05-13 19:35:40,847 server virtual display now set to 2560x1205
2024-05-13 19:35:40,852  automatic picture encoding enabled, also available:
2024-05-13 19:35:40,852   rgb24, rgb32, png, webp, jpeg
2024-05-13 19:35:40,884 Error spawning child 'no'
2024-05-13 19:35:40,884  [Errno 2] No such file or directory: 'no'
2024-05-13 19:35:40,889 DPI set to 96 x 96
2024-05-13 19:35:40,929 client   1 title= admin@0135394f4388: ~/bin
2024-05-13 19:35:40,934 client   1 startup complete
2024-05-13 19:35:40,935 client   1 connection-established
2024-05-13 19:35:40,937 client   1 received xdg start menu data
2024-05-13 19:35:40,937 client   1 audio media source open
2024-05-13 19:35:40,937 client   1 using audio codec string for vorbis+mka: audio/webm; codecs="vorbis"
2024-05-13 19:35:40,937 client   1 audio: requesting vorbis+mka stream from the server
2024-05-13 19:35:40,938 client   1 update encodings: encodings,encodings.core,encodings.allowed,encodings.lossless,encodings.with_speed,encodings.with_quality,encodings.with_lossless_mode
2024-05-13 19:35:40,974 using pulseaudio device:
2024-05-13 19:35:40,974  'Monitor of Xpra Speaker'
2024-05-13 19:35:41,203 client   1 audio-state: waiting
2024-05-13 19:35:41,203 client   1 audio-state: error
2024-05-13 19:35:41,204 client   1 audio: stopping stream
2024-05-13 19:35:41,204 client   1 close_audio_mediasource: audio_source_buffer=[object SourceBuffer], media_source=[object MediaSource], audio=[object HTMLAudioElement]
2024-05-13 19:35:41,204 client   1 audio-state: stopped
2024-05-13 19:35:41,206 audio capture stopping
2024-05-13 19:35:41,251 client   1 received end-of-stream from server
2024-05-13 19:35:41,251 client   1 audio: stopping stream
2024-05-13 19:35:41,251 client   1 close_audio_mediasource: audio_source_buffer=null, media_source=null, audio=null
2024-05-13 19:35:42,259 New tcp connection received
2024-05-13 19:35:42,259  from 'xxx.119.xxx.46:63480'
2024-05-13 19:35:42,260  on '0.0.0.0:10000'
2024-05-13 19:35:44,838 client   1 received xdg start menu data

and here's my cmdline to start the xpra session:

admin@eb9cd1f32a37:/tmp/xpra/100$ cat cmdline 
/usr/bin/xpra
start
:100
--webcam=no
--bell=no
--cursors=no
--microphone=no
--input-method=IBus
--idle-timeout=0
--server-idle-timeout=0
--start-after-connect=no
--bind-tcp=0.0.0.0:10000
--exit-with-children=yes
--start-child=xterm

[pfmiles]

Errr..there's so much 'no's in my cmdline file, maybe I misunderstood some of the options? I'll check it for now.

[totaam]

--start-after-connect=no

There you go.
You're asking the server to start the command no after a client connects.