We should only add the DjDT urls if it is enabled.

cms/urls.py

@@ -190,6 +190,7 @@ if settings.DEBUG:
     except ImportError:
         pass
 
+if 'debug_toolbar' in settings.INSTALLED_APPS:
     import debug_toolbar
     urlpatterns += (
         url(r'^__debug__/', include(debug_toolbar.urls)),

lms/urls.py

@@ -708,6 +708,7 @@ if settings.DEBUG:
     # in debug mode, allow any template to be rendered (most useful for UX reference templates)
     urlpatterns += url(r'^template/(?P<template>.+)$', 'debug.views.show_reference_template'),
 
+if 'debug_toolbar' in settings.INSTALLED_APPS:
     import debug_toolbar
     urlpatterns += (
         url(r'^__debug__/', include(debug_toolbar.urls)),