Open bug in launchpad.net:
https://bugs.launchpad.net/ubuntu/+source/pulseaudio/+bug/1421002

"Change Bluethoo."

#0  0x00007f69a77c6e37 in __GI_raise (sig=sig@entry=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:56
        resultvar = 0
        pid = 1793
        selftid = 1793
#1  0x00007f69a77c8528 in __GI_abort () at abort.c:89
        save_stage = 2
        act = {__sigaction_handler = {sa_handler = 0x10c979e, sa_sigaction = 0x10c979e}, sa_mask = {__val = {140091773812220, 107491707232, 140734560817648, 140734560817640, 1, 206158430316, 140088948293633, 140733193388038, 17602462, 17602457, 57259365588238080, 16853379, 17044288, 16900064, 140734560818000, 17043876}}, sa_flags = -1753329825, sa_restorer = 0x7f69977ead80}
        sigs = {__val = {32, 0 <repeats 15 times>}}
#2  0x00007f69977e4f68 in transport_speaker_gain_changed_cb (y=<optimized out>, t=<optimized out>, u=<optimized out>) at modules/bluetooth/module-bluetooth-device.c:1576
No locals.
#3  0x00007f69a8fbdffc in pa_hook_fire (hook=0x102f2b0, data=0xffae70) at pulsecore/hook-list.c:106
        slot = 0x101bb00
        next = <optimized out>
        result = PA_HOOK_OK
        __func__ = "pa_hook_fire"
        __PRETTY_FUNCTION__ = "pa_hook_fire"
#4  0x00007f69a17a2da6 in parse_audio_property (d=0x101dfe0, interface=0x1041340 "org.bluez.Headset", i=0x6, is_property_change=255) at modules/bluetooth/bluetooth-util.c:628
        value = 15
        transport = 0xffae70
        variant_i = {dummy1 = 0x10ae140, dummy2 = 0x7f6900600000, dummy3 = 108, dummy4 = 0, dummy5 = 17490320, dummy6 = 0, dummy7 = 17, dummy8 = 32767, dummy9 = 17490320, dummy10 = 0, dummy11 = 20, pad1 = 32767, pad2 = -1467155648, pad3 = 0x7fff518154b0}
        p = PROFILE_HSP
        tstamp_now = 0
        tstamp_prev = 55407133202
        m = 0x0
        __func__ = "parse_audio_property"
        __PRETTY_FUNCTION__ = "parse_audio_property"
#5  0x00007f69a17a66c3 in filter_cb (bus=0x701, m=0x10ae140, userdata=0x101dfe0) at modules/bluetooth/bluetooth-util.c:1023
        arg_i = {dummy1 = 0x10ae140, dummy2 = 0x7f6900600000, dummy3 = 108, dummy4 = 0, dummy5 = 17490248, dummy6 = 0, dummy7 = 134, dummy8 = 32767, dummy9 = 17490320, dummy10 = 0, dummy11 = 16, pad1 = 32767, pad2 = -1467155136, pad3 = 0x7fff518154b0}
        old_any_connected = true
        d = 0x101dfe0
        err = {name = 0x0, message = 0x0, dummy1 = 1, dummy2 = 0, dummy3 = 0, dummy4 = 0, dummy5 = 0, padding1 = 0x50}
        __func__ = "filter_cb"
        __PRETTY_FUNCTION__ = "filter_cb"
#6  0x00007f69a8699161 in dbus_connection_dispatch () from /tmp/apport_sandbox_M6XAT9/lib/x86_64-linux-gnu/libdbus-1.so.3
No symbol table info available.
#7  0x00007f69a8d71114 in dispatch_cb (ea=0xfd2168, ev=0x1046d20, userdata=<optimized out>) at pulsecore/dbus-util.c:55
        conn = <optimized out>
#8  0x00007f69a8afedca in dispatch_defer (m=0xfd2110) at pulse/mainloop.c:682
        e = 0x1046d20
        r = 0
#9  pa_mainloop_dispatch (m=m@entry=0xfd2110) at pulse/mainloop.c:895
        dispatched = 0
        __func__ = "pa_mainloop_dispatch"
        __PRETTY_FUNCTION__ = "pa_mainloop_dispatch"
#10 0x00007f69a8afefdc in pa_mainloop_iterate (m=0xfd2110, block=<optimized out>, retval=0x7fff51815658) at pulse/mainloop.c:935
        r = 0
#11 0x00007f69a8aff080 in pa_mainloop_run (m=0xfd2110, retval=0x7fff51815658) at pulse/mainloop.c:950
        r = <optimized out>
#12 0x0000000000407058 in main (argc=16589072, argv=0xff4a00) at daemon/main.c:1150
        c = 0xfd6440
        buf = 0xfdba80
        conf = 0xfca090
        mainloop = 0xfd2110
        configured_address = 0xfd2110 "\220L\377"
        retval = 0
        d = 3
        ltdl_init = false
        passed_fd = 16556176
        e = 0x0
        daemon_pipe = {-1, -1}
        daemon_pipe2 = {-1, -1}
        pid_monitor = 0xfcfab0
        server_lookup = 0xfdba80
        server_bus = 0xff4a00
        __func__ = "main"
        __PRETTY_FUNCTION__ = "main"