I have a similar error on Ubuntu 18.10 with Midori 0.5.11:

midori -g
Launching command: '/usr/bin/gdb' --batch -ex 'set print thread-events off' -ex run -ex 'set logging on /run/user/1000/midori/gdb.bt' -ex 'bt' --return-child-result --args midori 
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".

(midori4:5890): GLib-CRITICAL **: 17:42:26.233: g_atomic_ref_count_dec: assertion 'g_atomic_int_get (arc) > 0' failed

Thread 1 "midori" received signal SIGSEGV, Segmentation fault.
0x00007ffff6676205 in ?? () from /usr/lib/x86_64-linux-gnu/libwebkitgtk-1.0.so.0
#0  0x00007ffff6676205 in ?? () from /usr/lib/x86_64-linux-gnu/libwebkitgtk-1.0.so.0
#1  0x00007ffff65e2099 in ?? () from /usr/lib/x86_64-linux-gnu/libwebkitgtk-1.0.so.0
#2  0x00007ffff67502cb in ?? () from /usr/lib/x86_64-linux-gnu/libwebkitgtk-1.0.so.0
#3  0x00007ffff66e3487 in ?? () from /usr/lib/x86_64-linux-gnu/libwebkitgtk-1.0.so.0
#4  0x00007ffff66e5bfd in ?? () from /usr/lib/x86_64-linux-gnu/libwebkitgtk-1.0.so.0
#5  0x00007ffff65cf37b in ?? () from /usr/lib/x86_64-linux-gnu/libwebkitgtk-1.0.so.0
#6  0x00007ffff65a38ab in ?? () from /usr/lib/x86_64-linux-gnu/libwebkitgtk-1.0.so.0
#7  0x00007ffff65cc08c in ?? () from /usr/lib/x86_64-linux-gnu/libwebkitgtk-1.0.so.0
#8  0x00007ffff65cd486 in ?? () from /usr/lib/x86_64-linux-gnu/libwebkitgtk-1.0.so.0
#9  0x00007ffff65cf3e7 in ?? () from /usr/lib/x86_64-linux-gnu/libwebkitgtk-1.0.so.0
#10 0x00007ffff65a38ab in ?? () from /usr/lib/x86_64-linux-gnu/libwebkitgtk-1.0.so.0
#11 0x00007ffff65cc08c in ?? () from /usr/lib/x86_64-linux-gnu/libwebkitgtk-1.0.so.0
#12 0x00007ffff65cd486 in ?? () from /usr/lib/x86_64-linux-gnu/libwebkitgtk-1.0.so.0
#13 0x00007ffff65cf3e7 in ?? () from /usr/lib/x86_64-linux-gnu/libwebkitgtk-1.0.so.0
#14 0x00007ffff65a38ab in ?? () from /usr/lib/x86_64-linux-gnu/libwebkitgtk-1.0.so.0
#15 0x00007ffff65cc08c in ?? () from /usr/lib/x86_64-linux-gnu/libwebkitgtk-1.0.so.0
#16 0x00007ffff65cd486 in ?? () from /usr/lib/x86_64-linux-gnu/libwebkitgtk-1.0.so.0
#17 0x00007ffff65cf3e7 in ?? () from /usr/lib/x86_64-linux-gnu/libwebkitgtk-1.0.so.0
#18 0x00007ffff65a38ab in ?? () from /usr/lib/x86_64-linux-gnu/libwebkitgtk-1.0.so.0
#19 0x00007ffff65cc08c in ?? () from /usr/lib/x86_64-linux-gnu/libwebkitgtk-1.0.so.0
#20 0x00007ffff65cd486 in ?? () from /usr/lib/x86_64-linux-gnu/libwebkitgtk-1.0.so.0
#21 0x00007ffff65cf3e7 in ?? () from /usr/lib/x86_64-linux-gnu/libwebkitgtk-1.0.so.0
#22 0x00007ffff65a38ab in ?? () from /usr/lib/x86_64-linux-gnu/libwebkitgtk-1.0.so.0
#23 0x00007ffff65cc08c in ?? () from /usr/lib/x86_64-linux-gnu/libwebkitgtk-1.0.so.0
#24 0x00007ffff65cd486 in ?? () from /usr/lib/x86_64-linux-gnu/libwebkitgtk-1.0.so.0
#25 0x00007ffff65cf3e7 in ?? () from /usr/lib/x86_64-linux-gnu/libwebkitgtk-1.0.so.0
#26 0x00007ffff65a38ab in ?? () from /usr/lib/x86_64-linux-gnu/libwebkitgtk-1.0.so.0
#27 0x00007ffff674fa51 in ?? () from /usr/lib/x86_64-linux-gnu/libwebkitgtk-1.0.so.0
#28 0x00007ffff674fce0 in ?? () from /usr/lib/x86_64-linux-gnu/libwebkitgtk-1.0.so.0
#29 0x00007ffff6522bbc in ?? () from /usr/lib/x86_64-linux-gnu/libwebkitgtk-1.0.so.0
#30 0x00007ffff60afc38 in ?? () from /usr/lib/x86_64-linux-gnu/libwebkitgtk-1.0.so.0
#31 0x00007ffff6457e28 in ?? () from /usr/lib/x86_64-linux-gnu/libwebkitgtk-1.0.so.0
#32 0x00007ffff643339e in ?? () from /usr/lib/x86_64-linux-gnu/libwebkitgtk-1.0.so.0
#33 0x00007ffff649521a in ?? () from /usr/lib/x86_64-linux-gnu/libwebkitgtk-1.0.so.0
#34 0x00007ffff6495577 in ?? () from /usr/lib/x86_64-linux-gnu/libwebkitgtk-1.0.so.0
#35 0x00007ffff648bc11 in ?? () from /usr/lib/x86_64-linux-gnu/libwebkitgtk-1.0.so.0
#36 0x00007ffff5e90636 in ?? () from /usr/lib/x86_64-linux-gnu/libwebkitgtk-1.0.so.0
#37 0x00007ffff5eb0b52 in ?? () from /usr/lib/x86_64-linux-gnu/libwebkitgtk-1.0.so.0
#38 0x00007ffff7b66573 in ?? () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#39 0x00007ffff7b65ae8 in g_main_context_dispatch () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#40 0x00007ffff7b65ed8 in ?? () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#41 0x00007ffff7b661d2 in g_main_loop_run () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#42 0x00007ffff56273e7 in gtk_main () from /usr/lib/x86_64-linux-gnu/libgtk-x11-2.0.so.0
#43 0x0000555555557d1f in main ()

It opens the page but crashes after about 10 seconds.

greetinx