From 1ea820a50e46cf76eb0f6f14f5ca1f4434b5dd55 Mon Sep 17 00:00:00 2001
From: Jeremy Stretch <stretch@packetlife.net>
Date: Wed, 15 Jan 2020 10:23:07 -0500
Subject: [PATCH] Fixes #3900: Fix exception when deleting device types

---
 docs/release-notes/version-2.6.md | 1 +
 netbox/dcim/models.py             | 9 ++++++++-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/docs/release-notes/version-2.6.md b/docs/release-notes/version-2.6.md
index 792e8990a..e3ad87ad0 100644
--- a/docs/release-notes/version-2.6.md
+++ b/docs/release-notes/version-2.6.md
@@ -6,6 +6,7 @@
 
 ## Bug Fixes
 
+* [#3900](https://github.com/netbox-community/netbox/issues/3900) - Fix exception when deleting device types
 * [#3914](https://github.com/netbox-community/netbox/issues/3914) - Fix interface filter field when unauthenticated
 
 ---
diff --git a/netbox/dcim/models.py b/netbox/dcim/models.py
index 833fb483b..8ab3a37a3 100644
--- a/netbox/dcim/models.py
+++ b/netbox/dcim/models.py
@@ -38,11 +38,18 @@ class ComponentTemplateModel(models.Model):
         raise NotImplementedError()
 
     def to_objectchange(self, action):
+        # Annotate the parent DeviceType
+        try:
+            parent = getattr(self, 'device_type', None)
+        except ObjectDoesNotExist:
+            # The parent DeviceType has already been deleted
+            parent = None
+
         return ObjectChange(
             changed_object=self,
             object_repr=str(self),
             action=action,
-            related_object=self.device_type,
+            related_object=parent,
             object_data=serialize_object(self)
         )