'NoneType' object has no attribute 'choices'

[abhijitsharma1010]

After upgrading to v3.6.0 , when we click on virtual machine tab from the side menu, we get this error "'NoneType' object has no attribute 'choices' " same thing happens when we try to go in a Vm from change log and click on edit button.

Any help to resolve this will be very much appreciated.

[candlerb]

Works for me, so there's something about your system that's different. Do you have any customizations, e.g. custom fields on VirtualMachine?

Can you provide a backtrace? (Set DEBUG=True in configuration.py, or set ADMINS and EMAIL to have it automatically mailed to you whenever an exception occurs in production)

[candlerb]

OK, so from the SQL results, the custom field "Server" has no choice set (and I see no choice set was built for it).

How exactly was this defined in NB 3.5? If it was defined as type "Selection" then it should have had a comma-separated list of allowed choices, and this should have been migrated to a choice set. But if it was of type "Object" (e.g. pointing to a Device) then it should have remained as "Object" and not changed to "Selection".

[candlerb]

do I need to revert back to a 3.5 series build for the mean time?

You could create the missing Choice Set and attach it to the 'Server' custom field, and all should then be OK.

But it would be helpful if you could revert to 3.5.x to understand what went wrong in the upgrade, and if this is reproducible and raised as an issue, then I'd expect the migration will be fixed.

[abhijitsharma1010]

I did the upgrade to v3.6 from v3.5.8 on my production vm as well as my testing vm. faced the same issue on both.

[ludof54]

Hello, i got the same type of error after an upgrade from v3.4.4 to 3.6 when i go to Admin / Current config

[candlerb]

That's a different error. I think it's almost certainly issue #13622, which has been fixed in the 'develop' branch and should arrive in v3.6.1.

[abhijitsharma1010]

I upgraded to v3.6.1 and still i am getting this error.

[abhijitsharma1010]

Environment:

Request Method: GET
Request URL: https://10.40.122.145/virtualization/virtual-machines/

Django Version: 4.2.5
Python Version: 3.8.10
Installed Applications:
['django.contrib.admin',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.staticfiles',
'django.contrib.humanize',
'corsheaders',
'debug_toolbar',
'graphiql_debug_toolbar',
'django_filters',
'django_tables2',
'django_prometheus',
'graphene_django',
'mptt',
'rest_framework',
'social_django',
'taggit',
'timezone_field',
'core',
'account',
'circuits',
'dcim',
'ipam',
'extras',
'tenancy',
'users',
'utilities',
'virtualization',
'wireless',
'django_rq',
'drf_spectacular',
'drf_spectacular_sidecar']
Installed Middleware:
['graphiql_debug_toolbar.middleware.DebugToolbarMiddleware',
'django_prometheus.middleware.PrometheusBeforeMiddleware',
'corsheaders.middleware.CorsMiddleware',
'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',
'netbox.middleware.RemoteUserMiddleware',
'netbox.middleware.CoreMiddleware',
'netbox.middleware.MaintenanceModeMiddleware',
'django_prometheus.middleware.PrometheusAfterMiddleware']

Traceback (most recent call last):
File "/opt/netbox/venv/lib/python3.8/site-packages/django/core/handlers/exception.py", line 55, in inner
response = get_response(request)
File "/opt/netbox/venv/lib/python3.8/site-packages/django/core/handlers/base.py", line 197, in _get_response
response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/opt/netbox/venv/lib/python3.8/site-packages/django/views/generic/base.py", line 104, in view
return self.dispatch(request, *args, **kwargs)
File "/opt/netbox/netbox/netbox/views/generic/base.py", line 77, in dispatch
return super().dispatch(request, *args, **kwargs)
File "/opt/netbox/netbox/utilities/views.py", line 99, in dispatch
return super().dispatch(request, *args, **kwargs)
File "/opt/netbox/venv/lib/python3.8/site-packages/django/views/generic/base.py", line 143, in dispatch
return handler(request, *args, **kwargs)
File "/opt/netbox/netbox/netbox/views/generic/bulk_views.py", line 179, in get
'filter_form': self.filterset_form(request.GET, label_suffix='') if self.filterset_form else None,
File "/opt/netbox/netbox/netbox/forms/base.py", line 166, in init
super().init(*args, **kwargs)
File "/opt/netbox/netbox/utilities/forms/mixins.py", line 19, in init
super().init(*args, **kwargs)
File "/opt/netbox/netbox/extras/forms/mixins.py", line 30, in init
self._append_customfield_fields()
File "/opt/netbox/netbox/extras/forms/mixins.py", line 57, in _append_customfield_fields
self.fields[field_name] = self._get_form_field(customfield)
File "/opt/netbox/netbox/netbox/forms/base.py", line 181, in _get_form_field
return customfield.to_form_field(set_initial=False, enforce_required=False, enforce_visibility=False)
File "/opt/netbox/netbox/extras/models/customfields.py", line 426, in to_form_field
choices = self.choice_set.choices

Exception Type: AttributeError at /virtualization/virtual-machines/
Exception Value: 'NoneType' object has no attribute 'choices'

[candlerb]

Correct. #13622 ('NoneType' object has no attribute '_meta') is fixed by v3.6.1, but that's a different issue.

As explained earlier, your error is due to bad state in your database. To fix it, you'll need to create the missing ChoiceSet to your selection custom field.

Unless you can find a reproducible way to get your system into the state it's in, which you raise as a bug report, it's unlikely to be fixed in Netbox, since (so far) you're the only one to have observed it.

[abhijitsharma1010]

Hey @candlerb can you guide me on how can I rectify this issue in my setup.

[candlerb]

Choice sets are managed via the GUI, under Customization > Custom Field Choices. Once you have created one that matches your needs (I believe this is for your custom field called "Server"), go to Customization > Custom Fields and assign the choice set you've created to the custom field.