Custom field on circuit terminations causes AttributeError in branches

[jnovinger]

Plugin Version

v0.5.7

NetBox Version

v4.1.1

Python Version

3.8+

Steps to Reproduce

1. Create a Site
2. Create a circuit type
3. Create a Provider
4. Create a Custom Field Choice Set with the following choices:

   lc:LC
   sc:SC
   

5. Create a custom field on circuit terminations:
   • Type: Selection
   • Name: termination_type
   • Choice set: Reference the choice set created above
6. Create a circuit
7. Create a branch and activate it
8. In the branch, navigate to the circuit
9. Attempt to create a circuit termination A:
   • Type: Site
   • Site: Select the existing site
   • Custom field: Select a value from the choice set

Expected Behavior

The circuit termination should be created successfully with the custom field value set.

Observed Behavior

A server error is thrown:

<class 'AttributeError'>

'NoneType' object has no attribute 'items'

Python version: 3.12.3
NetBox version: 4.4.4-Docker-3.4.1
Plugins:
  netbox_branching: 0.7.1

Note: The same operation works correctly in the main branch. The error only occurs when attempting to create circuit terminations with custom fields while a branch is active.

[sinuscosinustan]

This is not limited circuit terminations, but can also happen on devices (specifically devices with module bays in combination with Integer custom fields).

Updating the device in the main branch works flawlessly, only in a different branch it'll break.

Device in DB:

netbox=# select * from branch_46zi23ye.dcim_device where id=149\gx
-[ RECORD 1 ]-------------+------------------------------
created                   | 2025-09-08 18:46:51.473056+00
last_updated              | 2025-10-31 09:18:37.755305+00
custom_field_data         | {"bgp_as": null}
id                        | 149
local_context_data        |
name                      | MicroCloud1
serial                    |
asset_tag                 | MC1
position                  | 11.0
face                      | front
status                    | active
vc_position               |
vc_priority               |
comments                  |
cluster_id                |
role_id                   | 1
device_type_id            | 36
location_id               |
platform_id               |
primary_ip4_id            |
primary_ip6_id            |
rack_id                   | 1
site_id                   | 1
tenant_id                 |
virtual_chassis_id        |
airflow                   | front-to-rear
description               |
config_template_id        |
latitude                  |
longitude                 |
oob_ip_id                 |
console_port_count        | 0
console_server_port_count | 0
power_port_count          | 0
power_outlet_count        | 0
interface_count           | 2
front_port_count          | 0
rear_port_count           | 0
device_bay_count          | 8
module_bay_count          | 2
inventory_item_count      | 0

Traceback from debug mode:

Environment:


Request Method: POST
Request URL: https://redacted-nb-instance.yikes/dcim/devices/149/edit/

Django Version: 5.2.7
Python Version: 3.12.3
Installed Applications:
['django.contrib.auth',
 'django.contrib.contenttypes',
 'django.contrib.sessions',
 'django.contrib.messages',
 'django.contrib.staticfiles',
 'django.contrib.humanize',
 'django.forms',
 'corsheaders',
 'debug_toolbar',
 'django_filters',
 'django_htmx',
 'django_tables2',
 'django_prometheus',
 'strawberry_django',
 'mptt',
 'rest_framework',
 'social_django',
 'sorl.thumbnail',
 'taggit',
 'timezone_field',
 'core',
 'account',
 'circuits',
 'dcim',
 'ipam',
 'extras',
 'tenancy',
 'users',
 'utilities',
 'virtualization',
 'vpn',
 'wireless',
 'django_rq',
 'drf_spectacular',
 'drf_spectacular_sidecar',
 'netbox_qrcode.QRCodeConfig',
 'netbox_cable_labels.AutoCableLabelsConfig',
 'netbox_branching.AppConfig']
Installed Middleware:
['strawberry_django.middlewares.debug_toolbar.DebugToolbarMiddleware',
 'corsheaders.middleware.CorsMiddleware',
 'django.contrib.sessions.middleware.SessionMiddleware',
 'django.middleware.locale.LocaleMiddleware',
 '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',
 'django_htmx.middleware.HtmxMiddleware',
 'netbox.middleware.RemoteUserMiddleware',
 'netbox.middleware.CoreMiddleware',
 'netbox.middleware.MaintenanceModeMiddleware',
 'netbox_branching.middleware.BranchMiddleware']



Traceback (most recent call last):
  File "/opt/netbox/venv/lib/python3.12/site-packages/django/core/handlers/exception.py", line 55, in inner
    response = get_response(request)
               ^^^^^^^^^^^^^^^^^^^^^
  File "/opt/netbox/venv/lib/python3.12/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/python3.12/site-packages/django/views/generic/base.py", line 105, in view
    return self.dispatch(request, *args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/netbox/netbox/netbox/views/generic/object_views.py", line 190, in dispatch
    return super().dispatch(request, *args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/netbox/netbox/netbox/views/generic/base.py", line 26, in dispatch
    return super().dispatch(request, *args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/netbox/netbox/utilities/views.py", line 144, in dispatch
    return super().dispatch(request, *args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/netbox/netbox/utilities/views.py", line 45, in dispatch
    return super().dispatch(request, *args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/netbox/venv/lib/python3.12/site-packages/django/views/generic/base.py", line 144, in dispatch
    return handler(request, *args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/netbox/netbox/netbox/views/generic/object_views.py", line 297, in post
    obj = form.save()
          ^^^^^^^^^^^
  File "/opt/netbox/venv/lib/python3.12/site-packages/django/forms/models.py", line 554, in save
    self.instance.save()
    ^^^^^^^^^^^^^^^^^^^^
  File "/opt/netbox/netbox/dcim/models/devices.py", line 1014, in save
    device.save()
    ^^^^^^^^^^^^^
  File "/opt/netbox/netbox/dcim/models/devices.py", line 989, in save
    super().save(*args, **kwargs)
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/netbox/netbox/utilities/tracking.py", line 56, in save
    super().save(*args, **kwargs)
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/netbox/netbox/netbox/models/features.py", line 324, in save
    super().save(*args, **kwargs)
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/netbox/venv/lib/python3.12/site-packages/django/db/models/base.py", line 902, in save
    self.save_base(
    ^
  File "/opt/netbox/venv/lib/python3.12/site-packages/django/db/models/base.py", line 1023, in save_base
    post_save.send(
    ^
  File "/opt/netbox/venv/lib/python3.12/site-packages/django/dispatch/dispatcher.py", line 189, in send
    response = receiver(signal=self, sender=sender, **named)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/netbox/netbox/core/signals.py", line 143, in handle_changed_object
    objectchange.save()
    ^^^^^^^^^^^^^^^^^^^
  File "/opt/netbox/netbox/core/models/change_logging.py", line 142, in save
    return super().save(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/netbox/venv/lib/python3.12/site-packages/django/db/models/base.py", line 902, in save
    self.save_base(
    ^
  File "/opt/netbox/venv/lib/python3.12/site-packages/django/db/models/base.py", line 1023, in save_base
    post_save.send(
    ^
  File "/opt/netbox/venv/lib/python3.12/site-packages/django/dispatch/dispatcher.py", line 189, in send
    response = receiver(signal=self, sender=sender, **named)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/netbox/venv/lib/python3.12/site-packages/netbox_branching/signal_receivers.py", line 97, in record_change_diff
    diff.save()
    ^^^^^^^^^^^
  File "/opt/netbox/venv/lib/python3.12/site-packages/netbox_branching/models/changes.py", line 181, in save
    self._update_conflicts()
    ^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/netbox/venv/lib/python3.12/site-packages/netbox_branching/models/changes.py", line 197, in _update_conflicts
    k for k, v in self.original.items()
                  ^^^^^^^^^^^^^^^^^^^

Exception Type: AttributeError at /dcim/devices/149/edit/
Exception Value: 'NoneType' object has no attribute 'items'

[cruse1977]

Note. I'm also seeing this without custom fields. We may need to triage as circuit terminations first.

[arthanson]

This should be fixed by change from #350 as it checks if self.original value exists before continuing.