Confirmed in all cases it's just that the X11/Xmir apps can't detect the session bus address of the login (which is on a different TTY BTW). Forcing DBUS_SESSION_BUS_ADDRESS solves the problem. Here are some stack traces of the hangs: gedit: (gdb) bt #0 0x00007ffff705e853 in select () at ../sysdeps/unix/syscall-template.S:84 #1 0x00007ffff477acd1 in g_spawn_sync () from /lib/x86_64-linux-gnu/libglib-2.0.so.0 #2 0x00007ffff477b313 in g_spawn_command_line_sync () from /lib/x86_64-linux-gnu/libglib-2.0.so.0 #3 0x00007ffff7862b70 in ?? () from /usr/lib/x86_64-linux-gnu/libgio-2.0.so.0 #4 0x00007ffff78645f2 in g_dbus_address_get_for_bus_sync () from /usr/lib/x86_64-linux-gnu/libgio-2.0.so.0 #5 0x00007ffff786f7ee in ?? () from /usr/lib/x86_64-linux-gnu/libgio-2.0.so.0 #6 0x00007ffff787522b in g_bus_get_sync () from /usr/lib/x86_64-linux-gnu/libgio-2.0.so.0 #7 0x00007ffff784b969 in ?? () from /usr/lib/x86_64-linux-gnu/libgio-2.0.so.0 #8 0x00007ffff78488f3 in g_application_register () from /usr/lib/x86_64-linux-gnu/libgio-2.0.so.0 #9 0x00007ffff784918f in ?? () from /usr/lib/x86_64-linux-gnu/libgio-2.0.so.0 #10 0x00007ffff78494f2 in g_application_run () from /usr/lib/x86_64-linux-gnu/libgio-2.0.so.0 #11 0x0000000000400cfa in main () nautilus: (gdb) bt #0 0x00007ffff34c9833 in __select_nocancel () at ../sysdeps/unix/syscall-template.S:84 #1 0x00007ffff418ecd1 in g_spawn_sync () from /lib/x86_64-linux-gnu/libglib-2.0.so.0 #2 0x00007ffff418f313 in g_spawn_command_line_sync () from /lib/x86_64-linux-gnu/libglib-2.0.so.0 #3 0x00007ffff4729b70 in ?? () from /usr/lib/x86_64-linux-gnu/libgio-2.0.so.0 #4 0x00007ffff472b5f2 in g_dbus_address_get_for_bus_sync () from /usr/lib/x86_64-linux-gnu/libgio-2.0.so.0 #5 0x00007ffff47367ee in ?? () from /usr/lib/x86_64-linux-gnu/libgio-2.0.so.0 #6 0x00007ffff473c22b in g_bus_get_sync () from /usr/lib/x86_64-linux-gnu/libgio-2.0.so.0 #7 0x00007ffff4712969 in ?? () from /usr/lib/x86_64-linux-gnu/libgio-2.0.so.0 #8 0x00007ffff470f8f3 in g_application_register () from /usr/lib/x86_64-linux-gnu/libgio-2.0.so.0 #9 0x000000000042c78e in ?? () #10 0x00007fffedd29e40 in ffi_call_unix64 () from /usr/lib/x86_64-linux-gnu/libffi.so.6 #11 0x00007fffedd298ab in ffi_call () from /usr/lib/x86_64-linux-gnu/libffi.so.6 #12 0x00007ffff441fcf5 in g_cclosure_marshal_generic_va () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0 #13 0x00007ffff441f1d4 in ?? () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0 #14 0x00007ffff44394b8 in g_signal_emit_valist () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0 #15 0x00007ffff443a08f in g_signal_emit () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0 #16 0x00007ffff4710168 in ?? () from /usr/lib/x86_64-linux-gnu/libgio-2.0.so.0 #17 0x00007ffff47104f2 in g_application_run () from /usr/lib/x86_64-linux-gnu/libgio-2.0.so.0 #18 0x000000000042ba31 in ?? () #19 0x00007ffff33ed7e0 in __libc_start_main (main=0x42b970, argc=1, argv=0x7fffffffe5b8, init=, fini=, rtld_fini=, stack_end=0x7fffffffe5a8) at ../csu/libc-start.c:291 #20 0x000000000042ba99 in ?? () /usr/games/sol: (gdb) bt #0 0x00007ffff537556d in read () at ../sysdeps/unix/syscall-template.S:84 #1 0x00007ffff0fdacf8 in _dbus_read () from /lib/x86_64-linux-gnu/libdbus-1.so.3 #2 0x00007ffff0fde349 in ?? () from /lib/x86_64-linux-gnu/libdbus-1.so.3 #3 0x00007ffff0fd2c95 in ?? () from /lib/x86_64-linux-gnu/libdbus-1.so.3 #4 0x00007ffff0fd2b3a in ?? () from /lib/x86_64-linux-gnu/libdbus-1.so.3 #5 0x00007ffff0fbd32f in ?? () from /lib/x86_64-linux-gnu/libdbus-1.so.3 #6 0x00007ffff0fb8e08 in ?? () from /lib/x86_64-linux-gnu/libdbus-1.so.3 #7 0x00007fffedc925f6 in atspi_get_a11y_bus () from /usr/lib/x86_64-linux-gnu/libatspi.so.0 #8 0x00007ffff39e9052 in atk_bridge_adaptor_init () from /usr/lib/x86_64-linux-gnu/libatk-bridge-2.0.so.0 #9 0x00007ffff7117134 in ?? () from /usr/lib/x86_64-linux-gnu/libgtk-3.so.0 #10 0x00007ffff5f3dfa5 in g_closure_invoke () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0 #11 0x00007ffff5f4ffc1 in ?? () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0 #12 0x00007ffff5f58d5c in g_signal_emit_valist () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0 #13 0x00007ffff5f5908f in g_signal_emit () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0 #14 0x00007ffff5f424d4 in ?? () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0 #15 0x00007ffff5f44961 in g_object_notify () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0 #16 0x00007ffff6de5778 in ?? () from /usr/lib/x86_64-linux-gnu/libgdk-3.so.0 #17 0x00007ffff5f3e1d4 in ?? () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0 #18 0x00007ffff5f589a6 in g_signal_emit_valist () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0 #19 0x00007ffff5f59555 in g_signal_emit_by_name () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0 #20 0x00007ffff6e0b6c5 in ?? () from /usr/lib/x86_64-linux-gnu/libgdk-3.so.0 #21 0x00007ffff6de5646 in gdk_display_manager_open_display () from /usr/lib/x86_64-linux-gnu/libgdk-3.so.0 #22 0x00007ffff72a2266 in ?? () from /usr/lib/x86_64-linux-gnu/libgtk-3.so.0 #23 0x00007ffff5c71fc8 in g_option_context_parse () from /lib/x86_64-linux-gnu/libglib-2.0.so.0 #24 0x000055555556c1d6 in ?? () #25 0x00007ffff55fbc5d in ?? () from /usr/lib/x86_64-linux-gnu/libguile-2.0.so.22 #26 0x00007ffff55d458a in ?? () from /usr/lib/x86_64-linux-gnu/libguile-2.0.so.22 #27 0x00007ffff5671d33 in ?? () from /usr/lib/x86_64-linux-gnu/libguile-2.0.so.22 #28 0x00007ffff55de283 in scm_call_4 () from /usr/lib/x86_64-linux-gnu/libguile-2.0.so.22 #29 0x00007ffff55d4d21 in ?? () from /usr/lib/x86_64-linux-gnu/libguile-2.0.so.22 #30 0x00007ffff55d4e05 in scm_c_with_continuation_barrier () from /usr/lib/x86_64-linux-gnu/libguile-2.0.so.22 #31 0x00007ffff5654bbc in ?? () from /usr/lib/x86_64-linux-gnu/libguile-2.0.so.22 #32 0x00007fffeeccc952 in GC_call_with_stack_base () from /usr/lib/x86_64-linux-gnu/libgc.so.1 #33 0x00007ffff5654fe8 in scm_with_guile () from /usr/lib/x86_64-linux-gnu/libguile-2.0.so.22 #34 0x00007ffff55fbe35 in scm_boot_guile () from /usr/lib/x86_64-linux-gnu/libguile-2.0.so.22 #35 0x0000555555560861 in ?? () #36 0x00007ffff4fbc7e0 in __libc_start_main (main=0x5555555607d0, argc=1, argv=0x7fffffffe5b8, init=, fini=, rtld_fini=, stack_end=0x7fffffffe5a8) at ../csu/libc-start.c:291 #37 0x00005555555608c9 in ?? ()