Comment 3 for bug 1754084

See also https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=890882

I just recompiled from upstream git repo, and same problem.
(w/ X11)

I did:
$ lxc launch images:ubuntu/bionic/amd64 b
to get a fresh system, and followed the build instructions from https://www.freecadweb.org/wiki/CompileOnUnix

I used instructions from https://blog.simos.info/how-to-run-graphics-accelerated-gui-apps-in-lxd-containers-on-your-ubuntu-desktop/ to get an lxc image that has accelerated X11 access, glxinfo and xclock run ok.

I tried adding XInitThreads() into main() before Gui::Application::runApplication(), but no change.

The bt is:

(gdb) bt
#0 0x00007ffff4379e97 in __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:51
#1 0x00007ffff437b801 in __GI_abort () at abort.c:79
#2 0x00007ffff436b39a in __assert_fail_base (fmt=0x7ffff44f27d8 "%s%s%s:%u: %s%sAssertion `%s' failed.\n%n", assertion=assertion@entry=0x7ffff4d7f660 "!xcb_xlib_threads_sequence_lost", file=file@entry=0x7ffff4d7f4cb "../../src/xcb_io.c", line=line@entry=259, function=function@entry=0x7ffff4d7f908 "poll_for_event") at assert.c:92
#3 0x00007ffff436b412 in __GI___assert_fail (assertion=0x7ffff4d7f660 "!xcb_xlib_threads_sequence_lost", file=0x7ffff4d7f4cb "../../src/xcb_io.c", line=259, function=0x7ffff4d7f908 "poll_for_event")
    at assert.c:101
#4 0x00007ffff4d0d1da in () at /usr/lib/x86_64-linux-gnu/libX11.so.6
#5 0x00007ffff4d0d28b in () at /usr/lib/x86_64-linux-gnu/libX11.so.6
#6 0x00007ffff4d0d57d in _XEventsQueued () at /usr/lib/x86_64-linux-gnu/libX11.so.6
#7 0x00007ffff4d103c5 in _XGetRequest () at /usr/lib/x86_64-linux-gnu/libX11.so.6
#8 0x00007fffdefc4ee2 in () at /usr/lib/x86_64-linux-gnu/libGLX_mesa.so.0
#9 0x00007ffff2a06ff4 in () at /usr/lib/x86_64-linux-gnu/libQtOpenGL.so.4
#10 0x00007ffff298a8ad in QGLFormat::openGLVersionFlags() () at /usr/lib/x86_64-linux-gnu/libQtOpenGL.so.4
#11 0x00007ffff72e2a38 in Gui::Application::runApplication() () at /usr/local/lib/libFreeCADGui.so
#12 0x000055555555742b in main ()