Bail out of the client / shadow server if we can't.
Is that for MacOS only?
I think I've seen a case that I cannot start the shadow server for a Bionic laptop, freshly rebooted.
u@h:~$ xpra shadow ssh://ho@ho 2020-03-31 16:45:45,066 Xpra GTK3 X11 client version 3.0.8-r25767 64-bit 2020-03-31 16:45:45,130 running on Linux Ubuntu 16.04 xenial 2020-03-31 16:45:45,131 window manager is 'Xpra' 2020-03-31 16:45:45,278 No OpenGL_accelerate module loaded: No module named 'OpenGL_accelerate' (xpra:2406): Gdk-ERROR **: The program 'xpra' received an X Window System error. This probably reflects a bug in the program. The error was 'BadValue (integer parameter out of range for operation)'. (Details: serial 231 error_code 2 request_code 151 (GLX) minor_code 3) (Note to programmers: normally, X errors are reported asynchronously; that is, you will receive the error a while after causing it. To debug your program, run it with the GDK_SYNCHRONIZE environment variable to change this behavior. You can then get a meaningful backtrace from your debugger if you break on the gdk_x_error() function.) Trace/breakpoint trap (core dumped) u@h:~$ ssh ho@ho # Bionic here ho@ho:~$ xpra shadow :0 ho@ho:~$ Entering daemon mode; any further errors will be reported to: /run/user/1000/xpra/display-:0-20200331-164817.log cd /run/user/1000/xpra/ ho@ho:~$ cat display-\:0-20200331-164817.log 2020-03-31 16:48:20,360 Error: failed to connect to display :0 2020-03-31 16:48:20,360 could not connect to X server on display ':0' after 3 seconds
this ticket has been moved to: https://github.com/Xpra-org/xpra/issues/2691