https://bugzilla.redhat.com/show_bug.cgi?id=2346618
--- Comment #12 from fujiwara tfujiwar@redhat.com --- I guess you customized the desktop theme and it didn't has the "gtk-theme-name" property.
(In reply to satekambing from comment #11)
Created attachment 2077098 [details] File: backtrace
Thread 1 (Thread 0x7f4bad1c4080 (LWP 2549)): #0 0x00007f4bad5a04e0 in ?? () No symbol table info available. #1 0x00007f4bac7d67da in g_closure_invoke (closure=0x55d2777b05f0, return_value=0x0, n_param_values=2, param_values=0x7ffc1d70f640, invocation_hint=0x7ffc1d70f590) at ../gobject/gclosure.c:833 #2 0x00007f4bac8068f3 in signal_emit_unlocked_R.isra.0 (node=node@entry=0x7ffc1d70f750, detail=detail@entry=804, instance=instance@entry=0x55d27773d620, emission_return=emission_return@entry=0x0, instance_and_params=instance_and_params@entry=0x7ffc1d70f640) ... #8 g_object_notify_by_pspec (object=0x55d27773d620, pspec=0x55d27772ed00) at ../gobject/gobject.c:2030 __func__ = "g_object_notify_by_pspec" #9 0x00007f4bacc8c5c8 in gtk_settings_reset_property (settings=settings@entry=0x55d27773d620, name=name@entry=0x55d254214b7c "gtk-theme-name") at ../gtk/gtksettings.c:3665 #10 0x000055d254201bd9 in binding_common_set_custom_theme (settings_panel=<optimized out>) at /usr/src/debug/ibus-1.5.31-1.fc41.x86_64/ui/gtk3/bindingcommon.vala:237 ... #21 0x00007f4bac7f7733 in g_signal_emit (instance=instance@entry=0x55d2777dd7a0, signal_id=<optimized out>, detail=detail@entry=0) at ../gobject/gsignal.c:3582 #22 0x00007f4bac8ed68b in settings_backend_path_changed (backend=<optimized out>, path=<optimized out>, origin_tag=<optimized out>, target=0x55d2777dd7a0) at ../gio/gsettings.c:460 #23 settings_backend_path_changed (target=0x55d2777dd7a0, backend=<optimized out>, path=<optimized out>, origin_tag=<optimized out>) at ../gio/gsettings.c:451 #24 0x00007f4bac8ea866 in g_settings_backend_invoke_closure (user_data=user_data@entry=0x7f4b8c003850) at ../gio/gsettingsbackend.c:270 closure = 0x7f4b8c003850 #25 0x00007f4bac6c5add in g_idle_dispatch (source=0x7f4b8c007ea0, callback=0x7f4bac8ea840 <g_settings_backend_invoke_closure>, user_data=0x7f4b8c003850) at ../glib/gmain.c:6243 #26 0x00007f4bac6bf28c in g_main_dispatch (context=0x55d2776db740) at ../glib/gmain.c:3357