Comment 2 for bug 1521789

I just upgraded to 15.10. I created a new account to replicate the bug, so no old settings would interfere.

I launch firefox, go through some tabs, and within a few minutes it freezes. This happens over and over when I try to use firefox. This did not happen on 15.04. But when I upgraded to 15.10, it started happening. Again, I just created this account on this machine, so it has all the default settings.

I did all the apt-get upgrades and rebooted the machine right before launching firefox to capture this last freeze.

Here is what it says on the command line:

$ firefox
org.gtk.vfs.MountTracker.listMountableInfo call failed: GDBus.Error:org.freedesktop.DBus.Error.AccessDenied: An AppArmor policy prevents this sender from sending this message to this recipient; type="method_call", sender=":1.168" (uid=1003 pid=11496 comm="/usr/lib/firefox/firefox ") interface="org.gtk.vfs.MountTracker" member="ListMountableInfo" error name="(unset)" requested_reply="0" destination=":1.9" (uid=1003 pid=3125 comm="/usr/lib/gvfs/gvfsd ") (g-dbus-error-quark, 9)
org.gtk.vfs.MountTracker.listMountableInfo call failed: GDBus.Error:org.freedesktop.DBus.Error.AccessDenied: An AppArmor policy prevents this sender from sending this message to this recipient; type="method_call", sender=":1.171" (uid=1003 pid=11572 comm="/usr/lib/firefox/plugin-container -greomni /usr/li") interface="org.gtk.vfs.MountTracker" member="ListMountableInfo" error name="(unset)" requested_reply="0" destination=":1.9" (uid=1003 pid=3125 comm="/usr/lib/gvfs/gvfsd ") (g-dbus-error-quark, 9)
Vector smash protection is enabled.
2.4+ kernel w/o ELF notes? -- report this

(firefox:11496): GStreamer-WARNING **: External plugin loader failed. This most likely means that the plugin loader helper binary was not found or could not be run. You might need to set the GST_PLUGIN_SCANNER environment variable if your setup is unusual. This should normally not be required though.

(firefox:11496): GLib-GObject-WARNING **: cannot register existing type 'GdkDisplay'

(firefox:11496): GLib-CRITICAL **: g_once_init_leave: assertion 'result != 0' failed

(firefox:11496): GLib-GObject-CRITICAL **: g_type_register_static: assertion 'parent_type > 0' failed

(firefox:11496): GLib-GObject-CRITICAL **: g_type_add_interface_static: assertion 'G_TYPE_IS_INSTANTIATABLE (instance_type)' failed

(firefox:11496): GLib-CRITICAL **: g_once_init_leave: assertion 'result != 0' failed
d^C
testacct@backus:~/e$ [Child 11572] ###!!! ABORT: Aborting on channel error.: file /build/firefox-undGCc/firefox-42.0+build2/ipc/glue/MessageChannel.cpp, line 1768
[Child 11572] ###!!! ABORT: Aborting on channel error.: file /build/firefox-undGCc/firefox-42.0+build2/ipc/glue/MessageChannel.cpp, line 1768