Yeah, I get this on mine too..

mythbuntu@mythbuntu:/var/log/installer$ cat debug 
Ubiquity 2.18.7
Gtk-Message: Failed to load module "overlay-scrollbar"

(ubiquity:2604): Gtk-CRITICAL **: gtk_radio_button_set_group: assertion '!g_slist_find (group, radio_button)' failed

(ubiquity:2604): Gtk-CRITICAL **: gtk_radio_button_set_group: assertion '!g_slist_find (group, radio_button)' failed
No such schema 'org.gnome.nautilus.desktop'
update_release_notes_label()
update_release_notes_label()

(ubiquity:2604): Gtk-CRITICAL **: gtk_widget_set_allocation: assertion 'gtk_widget_get_visible (widget) || gtk_widget_is_toplevel (widget)' failed

(ubiquity:2604): Gtk-CRITICAL **: gtk_widget_set_allocation: assertion 'gtk_widget_get_visible (widget) || gtk_widget_is_toplevel (widget)' failed

(ubiquity:2604): Gtk-CRITICAL **: gtk_widget_set_allocation: assertion 'gtk_widget_get_visible (widget) || gtk_widget_is_toplevel (widget)' failed

(ubiquity:2604): Gtk-CRITICAL **: gtk_widget_set_allocation: assertion 'gtk_widget_get_visible (widget) || gtk_widget_is_toplevel (widget)' failed
No such schema 'com.canonical.indicator.session'
No such schema 'com.canonical.indicator.session'
No such schema 'com.canonical.indicator.session'
No such schema 'com.canonical.indicator.session'
locale.setlocale failed: unsupported locale setting (LANG=en_GB.UTF-8)
/usr/lib/ubiquity/plugins/ubi-console-setup.py:72: Warning: Source ID 5323 was not found when attempting to remove it
  GLib.source_remove(self.keyboard_layout_timeout_id)
/usr/lib/ubiquity/plugins/ubi-console-setup.py:74: Warning: Source ID 5326 was not found when attempting to remove it
  GLib.source_remove(self.keyboard_variant_timeout_id)
Exception in GTK frontend (invoking crash handler):
Traceback (most recent call last):
  File "/usr/lib/ubiquity/ubiquity/frontend/gtk_ui.py", line 778, in <lambda>
    lambda: self.dbfilter.start(auto_process=True))
  File "/usr/lib/ubiquity/ubiquity/filteredcommand.py", line 103, in start
    prep = self.prepare()
  File "/usr/lib/ubiquity/plugins/myth-drivers.py", line 112, in prepare
    drivers = self.ui.get_drivers()
  File "/usr/lib/ubiquity/plugins/myth-drivers.py", line 107, in get_drivers
    'tvstandard': self.tvoutstandard}])
  File "/usr/lib/python3/dist-packages/mythbuntu_common/installer.py", line 85, in build_static_list
    row = list[item].get_selection().get_selected_rows()[1]
AttributeError: 'ComboBox' object has no attribute 'get_selection'

Traceback (most recent call last):
  File "/usr/lib/ubiquity/ubiquity/frontend/gtk_ui.py", line 778, in <lambda>
    lambda: self.dbfilter.start(auto_process=True))
  File "/usr/lib/ubiquity/ubiquity/filteredcommand.py", line 103, in start
    prep = self.prepare()
  File "/usr/lib/ubiquity/plugins/myth-drivers.py", line 112, in prepare
    drivers = self.ui.get_drivers()
  File "/usr/lib/ubiquity/plugins/myth-drivers.py", line 107, in get_drivers
    'tvstandard': self.tvoutstandard}])
  File "/usr/lib/python3/dist-packages/mythbuntu_common/installer.py", line 85, in build_static_list
    row = list[item].get_selection().get_selected_rows()[1]
AttributeError: 'ComboBox' object has no attribute 'get_selection'
No such schema 'com.canonical.indicator.session'
No such schema 'com.canonical.indicator.session'
No such schema 'com.canonical.indicator.session'
No such schema 'com.canonical.indicator.session'
No such schema 'org.gnome.settings-daemon.plugins.power'
No such schema 'org.gnome.nautilus.desktop'