Unable to move pages into the sublevels: 'NoneType' object has no attribute 'allowed_subpage_models'

Found a bug? Please fill out the sections below. 👍

Issue Summary

I’m unable to move pages into the sublevels of the other pages.

Steps to Reproduce

Please create the following tree of pages:

root
├── page1
│   └── sub1
└── page2

Try to move sub1 into the page2. Enjoy the error page.

Technical details

wagtail==1.13.1

Environment:


Request Method: GET
Request URL: http://0.0.0.0:8000/admin/pages/16/move/6/

Django Version: 1.11.9
Python Version: 3.5.3
Installed Applications:
['transit',
 'home',
 'search',
 'wagtail.wagtailforms',
 'wagtail.wagtailredirects',
 'wagtail.wagtailembeds',
 'wagtail.wagtailsites',
 'wagtail.wagtailusers',
 'wagtail.wagtailsnippets',
 'wagtail.wagtaildocs',
 'wagtail.wagtailimages',
 'wagtail.wagtailsearch',
 'wagtail.wagtailadmin',
 'wagtail.wagtailcore',
 'wagtail.contrib.modeladmin',
 'wagtailmenus',
 'modelcluster',
 'taggit',
 'django.contrib.admin',
 'django.contrib.auth',
 'django.contrib.contenttypes',
 'django.contrib.sessions',
 'django.contrib.messages',
 'django.contrib.staticfiles',
 'wagtail.contrib.wagtailstyleguide',
 'debug_toolbar',
 'django_extensions']
Installed Middleware:
['django.contrib.sessions.middleware.SessionMiddleware',
 'django.middleware.common.CommonMiddleware',
 'django.middleware.csrf.CsrfViewMiddleware',
 'django.contrib.auth.middleware.AuthenticationMiddleware',
 'django.contrib.messages.middleware.MessageMiddleware',
 'django.middleware.clickjacking.XFrameOptionsMiddleware',
 'django.middleware.security.SecurityMiddleware',
 'wagtail.wagtailcore.middleware.SiteMiddleware',
 'wagtail.wagtailredirects.middleware.RedirectMiddleware',
 'debug_toolbar.middleware.DebugToolbarMiddleware']



Traceback:

File "/home/narunas/GIT/project/www/pyenv/lib/python3.5/site-packages/django/core/handlers/exception.py" in inner
  41.             response = get_response(request)

File "/home/narunas/GIT/project/www/pyenv/lib/python3.5/site-packages/django/core/handlers/base.py" in _get_response
  187.                 response = self.process_exception_by_middleware(e, request)

File "/home/narunas/GIT/project/www/pyenv/lib/python3.5/site-packages/django/core/handlers/base.py" in _get_response
  185.                 response = wrapped_callback(request, *callback_args, **callback_kwargs)

File "/home/narunas/GIT/project/www/pyenv/lib/python3.5/site-packages/django/views/decorators/cache.py" in _cache_controlled
  43.             response = viewfunc(request, *args, **kw)

File "/home/narunas/GIT/project/www/pyenv/lib/python3.5/site-packages/wagtail/wagtailadmin/urls/__init__.py" in wrapper
  96.             return view_func(request, *args, **kwargs)

File "/home/narunas/GIT/project/www/pyenv/lib/python3.5/site-packages/wagtail/wagtailadmin/decorators.py" in decorated_view
  31.             return view_func(request, *args, **kwargs)

File "/home/narunas/GIT/project/www/pyenv/lib/python3.5/site-packages/wagtail/wagtailadmin/views/pages.py" in move_choose_destination
  708.         target.can_choose = page_perms.can_move_to(target)

File "/home/narunas/GIT/project/www/pyenv/lib/python3.5/site-packages/wagtail/wagtailcore/models.py" in can_move_to
  1804.         if not self.page.specific.can_move_to(destination):

File "/home/narunas/GIT/project/www/pyenv/lib/python3.5/site-packages/wagtail/wagtailcore/models.py" in can_move_to
  998.         return self.can_exist_under(parent)

File "/home/narunas/GIT/project/www/pyenv/lib/python3.5/site-packages/wagtail/wagtailcore/models.py" in can_exist_under
  983.         return cls in parent.specific_class.allowed_subpage_models()

Exception Type: AttributeError at /admin/pages/16/move/6/
Exception Value: 'NoneType' object has no attribute 'allowed_subpage_models'

[narun4sk]

This problem occurred because my root page contained other pages created in the app which currently has been disabled in the settings. Re-enabling that app forced wagtail to behave.

I’m closing it as it perhaps is the intended behavior of the wagtail.

[zeroepix]

The other workaround for this issue, is if you know the pk of the target parent you can just manually construct the move URL.

e.g. if the page you want to move’s pk is 175, the root is 10, and the target is 197, it will check this URL first:

/admin/pages/175/move/10/ <- error

Just edit the URL and replace the 10 with the target’s pk instead (197 in this example), and hit enter:

/admin/pages/175/move/197/ <- will show you the target page and its children, assuming 175 can parent 197. /admin/pages/175/move/197/confirm/ <- will go straight to confirm button to save a click.

A built-in solution that could handle deleted models would be nice, as this workaround causes a lot of confusion for end-users.