diff --git a/netbox/dcim/api/serializers.py b/netbox/dcim/api/serializers.py
index af806acb8..85767201b 100644
--- a/netbox/dcim/api/serializers.py
+++ b/netbox/dcim/api/serializers.py
@@ -619,6 +619,24 @@ class PlatformSerializer(NetBoxModelSerializer):
         ]
 
 
+class CustomDeviceListSerializer(serializers.ListSerializer):
+    def validate(self, attrs):
+        validated_data = super().validate(attrs)
+        devices = [Device(**item) for item in validated_data]
+        # break these up into racks for space validation
+        racks = {}
+        for device in devices:
+            if device.rack:
+                if device.rack not in racks:
+                    racks[device.rack] = []
+                racks[device.rack].append(device)
+
+        for rack, devices in racks.items():
+            units = rack.check_for_space(devices)
+
+        return validated_data
+
+
 class DeviceSerializer(NetBoxModelSerializer):
     url = serializers.HyperlinkedIdentityField(view_name='dcim-api:device-detail')
     device_type = NestedDeviceTypeSerializer()
@@ -655,6 +673,7 @@ class DeviceSerializer(NetBoxModelSerializer):
             'primary_ip4', 'primary_ip6', 'cluster', 'virtual_chassis', 'vc_position', 'vc_priority', 'comments',
             'local_context_data', 'tags', 'custom_fields', 'created', 'last_updated',
         ]
+        list_serializer_class = CustomDeviceListSerializer
 
     @swagger_serializer_method(serializer_or_field=NestedDeviceSerializer)
     def get_parent_device(self, obj):
diff --git a/netbox/dcim/models/devices.py b/netbox/dcim/models/devices.py
index 5c41450a7..4334471ac 100644
--- a/netbox/dcim/models/devices.py
+++ b/netbox/dcim/models/devices.py
@@ -758,7 +758,7 @@ class Device(NetBoxModel, ConfigContextModel):
                     })
 
                 # Validate rack space
-                rack.check_for_space([self, ])
+                self.rack.check_for_space([self, ])
 
             except DeviceType.DoesNotExist:
                 pass
diff --git a/netbox/dcim/models/racks.py b/netbox/dcim/models/racks.py
index 49df8397b..8f7e35598 100644
--- a/netbox/dcim/models/racks.py
+++ b/netbox/dcim/models/racks.py
@@ -332,7 +332,7 @@ class Rack(NetBoxModel):
         :param exclude: List of devices IDs to exclude (useful when moving a device within a rack)
         """
         if exclude is not None:
-            devices = devices.exclude(pk__in=exclude)
+            devices = [device for device in devices if device.pk not in exclude]
 
         # Initialize the rack unit skeleton
         units = list(self.units)
@@ -369,7 +369,7 @@ class Rack(NetBoxModel):
         :param exclude: List of devices IDs to exclude (useful when moving a device within a rack)
         """
         # Gather all devices which consume U space within the rack
-        devices = self.get_all_devices()
+        devices = list(self.get_all_devices())
         return self.check_available_units(devices, u_height, rack_face, exclude)
 
     def check_for_space(self, devices):
@@ -377,13 +377,13 @@ class Rack(NetBoxModel):
         for device in devices:
             rack_face = device.face if not device.device_type.is_full_depth else None
             exclude_list = [device.pk] if device.pk else []
-            available_units = rack.check_available_units(
+            available_units = self.check_available_units(
                 rack_devices, u_height=device.device_type.u_height, rack_face=rack_face, exclude=exclude_list
             )
             if device.position and device.position not in available_units:
                 raise ValidationError({
-                    'position': f"U{self.position} is already occupied or does not have sufficient space to "
-                                f"accommodate this device type: {self.device_type} ({self.device_type.u_height}U)"
+                    'position': f"U{device.position} is already occupied or does not have sufficient space to "
+                                f"accommodate this device type: {device.device_type} ({device.device_type.u_height}U)"
                 })
 
             rack_devices.append(device)