diff --git a/netbox/core/tests/test_api.py b/netbox/core/tests/test_api.py
index 0c852636b..bf3d03c30 100644
--- a/netbox/core/tests/test_api.py
+++ b/netbox/core/tests/test_api.py
@@ -35,6 +35,9 @@ class DataSourceTestCase(APIViewTestCases.APIViewTestCase):
         'enabled': False,
         'description': 'foo bar baz',
     }
+    bulk_update_invalid_data = {
+        'owner': 99999,
+    }
 
     @classmethod
     def setUpTestData(cls):
diff --git a/netbox/tenancy/tests/test_api.py b/netbox/tenancy/tests/test_api.py
index dcba0025b..f53b19810 100644
--- a/netbox/tenancy/tests/test_api.py
+++ b/netbox/tenancy/tests/test_api.py
@@ -28,6 +28,9 @@ class TenantGroupTestCase(APIViewTestCases.APIViewTestCase):
         'description': 'New description',
         'comments': 'New Comment',
     }
+    bulk_update_invalid_data = {
+        'owner': 99999,
+    }
 
     @classmethod
     def setUpTestData(cls):
@@ -119,6 +122,9 @@ class TenantTestCase(APIViewTestCases.APIViewTestCase):
         'group': None,
         'description': 'New description',
     }
+    bulk_update_invalid_data = {
+        'owner': 99999,
+    }
 
     @classmethod
     def setUpTestData(cls):
@@ -160,6 +166,9 @@ class ContactGroupTestCase(APIViewTestCases.APIViewTestCase):
     bulk_update_data = {
         'description': 'New description',
     }
+    bulk_update_invalid_data = {
+        'owner': 99999,
+    }
 
     @classmethod
     def setUpTestData(cls):
@@ -219,6 +228,9 @@ class ContactRoleTestCase(APIViewTestCases.APIViewTestCase):
     bulk_update_data = {
         'description': 'New description',
     }
+    bulk_update_invalid_data = {
+        'owner': 99999,
+    }
 
     @classmethod
     def setUpTestData(cls):
@@ -238,6 +250,9 @@ class ContactTestCase(APIViewTestCases.APIViewTestCase):
         'groups': [],
         'comments': 'New comments',
     }
+    bulk_update_invalid_data = {
+        'owner': 99999,
+    }
 
     @classmethod
     def setUpTestData(cls):
@@ -277,6 +292,9 @@ class ContactAssignmentTestCase(APIViewTestCases.APIViewTestCase):
     bulk_update_data = {
         'priority': ContactPriorityChoices.PRIORITY_INACTIVE,
     }
+    bulk_update_invalid_data = {
+        'priority': 'not-a-valid-priority',
+    }
     user_permissions = ('tenancy.view_contact', )
 
     @classmethod
diff --git a/netbox/users/tests/test_api.py b/netbox/users/tests/test_api.py
index 1e5fd5ccf..22d6adf8b 100644
--- a/netbox/users/tests/test_api.py
+++ b/netbox/users/tests/test_api.py
@@ -24,6 +24,9 @@ class UserTestCase(APIViewTestCases.APIViewTestCase):
     bulk_update_data = {
         'email': 'test@example.com',
     }
+    bulk_update_invalid_data = {
+        'email': 'not-an-email',
+    }
 
     @classmethod
     def setUpTestData(cls):
@@ -202,6 +205,9 @@ class TokenTestCase(
     bulk_update_data = {
         'description': 'New description',
     }
+    bulk_update_invalid_data = {
+        'expires': 'not-a-date',
+    }
 
     def setUp(self):
         super().setUp()
@@ -588,6 +594,9 @@ class ObjectPermissionTestCase(
         cls.bulk_update_data = {
             'description': 'New description',
         }
+        cls.bulk_update_invalid_data = {
+            'users': [99999],
+        }
 
 
 class UserConfigTestCase(APITestCase):
@@ -649,6 +658,11 @@ class OwnerGroupTestCase(APIViewTestCases.APIViewTestCase):
     bulk_update_data = {
         'description': 'New description',
     }
+    # OwnerGroupSerializer exposes only name, description, and a read-only member_count, so an
+    # over-length description is the only value available to trigger a validation error.
+    bulk_update_invalid_data = {
+        'description': 'a' * 201,
+    }
 
     @classmethod
     def setUpTestData(cls):
@@ -750,3 +764,7 @@ class OwnerTestCase(APIViewTestCases.APIViewTestCase):
             'users': [users[3].pk],
             'description': 'New description',
         }
+
+        cls.bulk_update_invalid_data = {
+            'group': 99999,
+        }
diff --git a/netbox/virtualization/tests/test_api.py b/netbox/virtualization/tests/test_api.py
index f20c58653..9f00d79aa 100644
--- a/netbox/virtualization/tests/test_api.py
+++ b/netbox/virtualization/tests/test_api.py
@@ -56,6 +56,9 @@ class ClusterTypeTestCase(APIViewTestCases.APIViewTestCase):
     bulk_update_data = {
         'description': 'New description',
     }
+    bulk_update_invalid_data = {
+        'owner': 99999,
+    }
 
     @classmethod
     def setUpTestData(cls):
@@ -88,6 +91,9 @@ class ClusterGroupTestCase(APIViewTestCases.APIViewTestCase):
     bulk_update_data = {
         'description': 'New description',
     }
+    bulk_update_invalid_data = {
+        'owner': 99999,
+    }
 
     @classmethod
     def setUpTestData(cls):
@@ -107,6 +113,9 @@ class ClusterTestCase(APIViewTestCases.APIViewTestCase):
         'status': 'offline',
         'comments': 'New comment',
     }
+    bulk_update_invalid_data = {
+        'status': 'not-a-valid-status',
+    }
 
     @classmethod
     def setUpTestData(cls):
@@ -235,6 +244,9 @@ class VirtualMachineTypeTestCase(APIViewTestCases.APIViewTestCase):
             'default_memory': 8192,
             'description': 'New description',
         }
+        cls.bulk_update_invalid_data = {
+            'owner': 99999,
+        }
 
 
 class VirtualMachineTestCase(APIViewTestCases.APIViewTestCase):
@@ -243,6 +255,9 @@ class VirtualMachineTestCase(APIViewTestCases.APIViewTestCase):
     bulk_update_data = {
         'status': 'staged',
     }
+    bulk_update_invalid_data = {
+        'status': 'not-a-valid-status',
+    }
     user_permissions = ('dcim.view_platform', 'virtualization.view_virtualmachinetype')
 
     @classmethod
@@ -624,6 +639,9 @@ class VMInterfaceTestCase(APIViewTestCases.APIViewTestCase):
     bulk_update_data = {
         'description': 'New description',
     }
+    bulk_update_invalid_data = {
+        'mode': 'not-a-valid-mode',
+    }
     graphql_base_name = 'vm_interface'
     user_permissions = ('virtualization.view_virtualmachine', )
 
@@ -915,6 +933,9 @@ class VirtualDiskTestCase(APIViewTestCases.APIViewTestCase):
     bulk_update_data = {
         'size': 888,
     }
+    bulk_update_invalid_data = {
+        'virtual_machine': 99999,
+    }
     graphql_base_name = 'virtual_disk'
     user_permissions = ('virtualization.view_virtualmachine', )
 
diff --git a/netbox/wireless/tests/test_api.py b/netbox/wireless/tests/test_api.py
index b5671db32..bbfed9327 100644
--- a/netbox/wireless/tests/test_api.py
+++ b/netbox/wireless/tests/test_api.py
@@ -40,6 +40,9 @@ class WirelessLANGroupTestCase(APIViewTestCases.APIViewTestCase):
         'description': 'New description',
         'comments': 'New comment',
     }
+    bulk_update_invalid_data = {
+        'owner': 99999,
+    }
 
     @classmethod
     def setUpTestData(cls):
@@ -118,6 +121,10 @@ class WirelessLANTestCase(APIViewTestCases.APIViewTestCase):
             'auth_psk': 'abc123def456',
         }
 
+        cls.bulk_update_invalid_data = {
+            'auth_type': 'not-a-valid-auth-type',
+        }
+
 
 class WirelessLinkTestCase(APIViewTestCases.APIViewTestCase):
     model = WirelessLink
@@ -127,6 +134,9 @@ class WirelessLinkTestCase(APIViewTestCases.APIViewTestCase):
         'distance': 100,
         'distance_unit': 'm',
     }
+    bulk_update_invalid_data = {
+        'status': 'not-a-valid-status',
+    }
     user_permissions = ('dcim.view_interface', )
 
     @classmethod