This issue is similar to #58. The crash happens as in the referenced bug. Here is a stack trace:
(gdb) bt
#0 0x00007f1174ca0c39 in raise () from /usr/lib/libpthread.so.0
#1 0x00007f1171689776 in ?? () from /usr/lib/firefox/libxul.so
#2 0x00007f1171996b14 in ?? () from /usr/lib/firefox/libxul.so
#3 <signal handler called>
#4 0x00007f116d21a7f1 in ?? () from /usr/lib/libfontconfig.so.1
#5 0x00007f116d21a927 in ?? () from /usr/lib/libfontconfig.so.1
#6 0x00007f116d21b831 in FcConfigSubstituteWithPat ()
from /usr/lib/libfontconfig.so.1
#7 0x00007f116d22a06c in FcFontRenderPrepare ()
from /usr/lib/libfontconfig.so.1
#8 0x00007f1171cfc9c7 in ?? () from /usr/lib/firefox/libxul.so
#9 0x00007f1171cfdb10 in ?? () from /usr/lib/firefox/libxul.so
We no longer use the configuration from November 2014, so no such "fix" can be applied. Please, revise and update your fontconfig-iu installation as it seems to be causing the problems.
This issue is similar to #58. The crash happens as in the referenced bug. Here is a stack trace:
The fix suggested in #58 is applied in my setup