diff --git a/src/backend/InvenTree/InvenTree/api.py b/src/backend/InvenTree/InvenTree/api.py
index f4d481048a..e4da445cb4 100644
--- a/src/backend/InvenTree/InvenTree/api.py
+++ b/src/backend/InvenTree/InvenTree/api.py
@@ -229,11 +229,11 @@ class InfoApiSerializer(serializers.Serializer):
 
         logo = serializers.CharField()
         splash = serializers.CharField()
-        login_message = serializers.CharField()
-        navbar_message = serializers
+        login_message = serializers.CharField(allow_null=True)
+        navbar_message = serializers.CharField(allow_null=True)
 
     server = serializers.CharField(read_only=True)
-    id = serializers.CharField(read_only=True)
+    id = serializers.CharField(read_only=True, allow_null=True)
     version = serializers.CharField(read_only=True)
     instance = serializers.CharField(read_only=True)
     apiVersion = serializers.IntegerField(read_only=True)  # noqa: N815
@@ -246,15 +246,13 @@ class InfoApiSerializer(serializers.Serializer):
     email_configured = serializers.BooleanField(read_only=True)
     debug_mode = serializers.BooleanField(read_only=True)
     docker_mode = serializers.BooleanField(read_only=True)
-    default_locale = serializers.ChoiceField(
-        choices=settings.LOCALE_CODES, read_only=True
-    )
+    default_locale = serializers.CharField(read_only=True)
     customize = CustomizeSerializer(read_only=True)
     system_health = serializers.BooleanField(read_only=True)
     database = serializers.CharField(read_only=True)
     platform = serializers.CharField(read_only=True)
     installer = serializers.CharField(read_only=True)
-    target = serializers.CharField(read_only=True)
+    target = serializers.CharField(read_only=True, allow_null=True)
     django_admin = serializers.CharField(read_only=True)
     settings = SettingsSerializer(read_only=True, many=False)
 
diff --git a/src/backend/InvenTree/InvenTree/api_version.py b/src/backend/InvenTree/InvenTree/api_version.py
index de04146469..bbf63ceff5 100644
--- a/src/backend/InvenTree/InvenTree/api_version.py
+++ b/src/backend/InvenTree/InvenTree/api_version.py
@@ -1,13 +1,16 @@
 """InvenTree API version information."""
 
 # InvenTree API version
-INVENTREE_API_VERSION = 339
+INVENTREE_API_VERSION = 340
 
 """Increment this API version number whenever there is a significant change to the API that any clients need to know about."""
 
 
 INVENTREE_API_TEXT = """
 
+v340 -> 2025-04-15 : https://github.com/inventree/InvenTree/pull/9546
+    - Add nullable to various fields to make them not required
+
 v339 -> 2025-04-15 : https://github.com/inventree/InvenTree/pull/9283
     - Remove need for source in /plugins/ui/features
 
diff --git a/src/backend/InvenTree/build/serializers.py b/src/backend/InvenTree/build/serializers.py
index 84a5f1c517..aaef6bae81 100644
--- a/src/backend/InvenTree/build/serializers.py
+++ b/src/backend/InvenTree/build/serializers.py
@@ -1431,7 +1431,12 @@ class BuildLineSerializer(DataImportExportSerializerMixin, InvenTreeModelSeriali
         pricing=False,
     )
     build_detail = BuildSerializer(
-        label=_('Build'), source='build', part_detail=False, many=False, read_only=True
+        label=_('Build'),
+        source='build',
+        part_detail=False,
+        many=False,
+        read_only=True,
+        allow_null=True,
     )
 
     # Annotated (calculated) fields
diff --git a/src/backend/InvenTree/common/serializers.py b/src/backend/InvenTree/common/serializers.py
index c30ed95398..1931e35d72 100644
--- a/src/backend/InvenTree/common/serializers.py
+++ b/src/backend/InvenTree/common/serializers.py
@@ -812,6 +812,4 @@ class DataOutputSerializer(InvenTreeModelSerializer):
 
     user_detail = UserSerializer(source='user', read_only=True, many=False)
 
-    output = InvenTreeAttachmentSerializerField(
-        required=False, allow_null=True, read_only=True
-    )
+    output = InvenTreeAttachmentSerializerField(allow_null=True, read_only=True)
diff --git a/src/backend/InvenTree/company/serializers.py b/src/backend/InvenTree/company/serializers.py
index 3214595901..fa8605bcc3 100644
--- a/src/backend/InvenTree/company/serializers.py
+++ b/src/backend/InvenTree/company/serializers.py
@@ -169,7 +169,7 @@ class CompanySerializer(
         read_only=True,
     )
 
-    primary_address = AddressSerializer(required=False, allow_null=True, read_only=True)
+    primary_address = AddressSerializer(allow_null=True, read_only=True)
 
     image = InvenTreeImageSerializerField(required=False, allow_null=True)
 
@@ -463,7 +463,7 @@ class SupplierPartSerializer(
     )
 
     MPN = serializers.CharField(
-        source='manufacturer_part.MPN', read_only=True, label=_('MPN')
+        source='manufacturer_part.MPN', read_only=True, allow_null=True, label=_('MPN')
     )
 
     # Date fields
diff --git a/src/backend/InvenTree/importer/api.py b/src/backend/InvenTree/importer/api.py
index 96e8bacaf8..45bda7e430 100644
--- a/src/backend/InvenTree/importer/api.py
+++ b/src/backend/InvenTree/importer/api.py
@@ -65,7 +65,7 @@ class DataImporterModelSerializer(serializers.Serializer):
 
     serializer = serializers.CharField(read_only=True)
     model_type = serializers.CharField(read_only=True)
-    api_url = serializers.URLField(read_only=True)
+    api_url = serializers.URLField(read_only=True, allow_null=True)
 
 
 class DataImporterModelList(APIView):
diff --git a/src/backend/InvenTree/order/serializers.py b/src/backend/InvenTree/order/serializers.py
index 8034c735f6..2b9d81363b 100644
--- a/src/backend/InvenTree/order/serializers.py
+++ b/src/backend/InvenTree/order/serializers.py
@@ -112,11 +112,13 @@ class AbstractOrderSerializer(DataImportExportSerializerMixin, serializers.Seria
     import_exclude_fields = ['notes', 'duplicate']
 
     # Number of line items in this order
-    line_items = serializers.IntegerField(read_only=True, label=_('Line Items'))
+    line_items = serializers.IntegerField(
+        read_only=True, allow_null=True, label=_('Line Items')
+    )
 
     # Number of completed line items (this is an annotated field)
     completed_lines = serializers.IntegerField(
-        read_only=True, label=_('Completed Lines')
+        read_only=True, allow_null=True, label=_('Completed Lines')
     )
 
     # Human-readable status text (read-only)
@@ -156,7 +158,7 @@ class AbstractOrderSerializer(DataImportExportSerializerMixin, serializers.Seria
     )
 
     # Boolean field indicating if this order is overdue (Note: must be annotated)
-    overdue = serializers.BooleanField(required=False, read_only=True)
+    overdue = serializers.BooleanField(read_only=True, allow_null=True)
 
     barcode_hash = serializers.CharField(read_only=True)
 
@@ -609,7 +611,7 @@ class PurchaseOrderLineItemSerializer(
 
     received = serializers.FloatField(default=0, read_only=True)
 
-    overdue = serializers.BooleanField(required=False, read_only=True)
+    overdue = serializers.BooleanField(read_only=True, allow_null=True)
 
     total_price = serializers.FloatField(read_only=True)
 
@@ -632,7 +634,7 @@ class PurchaseOrderLineItemSerializer(
     )
 
     destination_detail = stock.serializers.LocationBriefSerializer(
-        source='get_destination', read_only=True
+        source='get_destination', read_only=True, allow_null=True
     )
 
     purchase_price_currency = InvenTreeCurrencySerializer(
@@ -652,14 +654,22 @@ class PurchaseOrderLineItemSerializer(
         write_only=True,
     )
 
-    sku = serializers.CharField(source='part.SKU', read_only=True, label=_('SKU'))
+    sku = serializers.CharField(
+        source='part.SKU', read_only=True, allow_null=True, label=_('SKU')
+    )
 
     mpn = serializers.CharField(
-        source='part.manufacturer_part.MPN', read_only=True, label=_('MPN')
+        source='part.manufacturer_part.MPN',
+        read_only=True,
+        allow_null=True,
+        label=_('MPN'),
     )
 
     ipn = serializers.CharField(
-        source='part.part.IPN', read_only=True, label=_('Internal Part Number')
+        source='part.part.IPN',
+        read_only=True,
+        allow_null=True,
+        label=_('Internal Part Number'),
     )
 
     internal_part = serializers.PrimaryKeyRelatedField(
@@ -1078,10 +1088,12 @@ class SalesOrderSerializer(
         source='customer', many=False, read_only=True, allow_null=True
     )
 
-    shipments_count = serializers.IntegerField(read_only=True, label=_('Shipments'))
+    shipments_count = serializers.IntegerField(
+        read_only=True, allow_null=True, label=_('Shipments')
+    )
 
     completed_shipments_count = serializers.IntegerField(
-        read_only=True, label=_('Completed Shipments')
+        read_only=True, allow_null=True, label=_('Completed Shipments')
     )
 
 
@@ -1253,7 +1265,7 @@ class SalesOrderLineItemSerializer(
     )
 
     # Annotated fields
-    overdue = serializers.BooleanField(required=False, read_only=True)
+    overdue = serializers.BooleanField(read_only=True, allow_null=True)
     available_stock = serializers.FloatField(read_only=True)
     available_variant_stock = serializers.FloatField(read_only=True)
     on_order = serializers.FloatField(label=_('On Order'), read_only=True)
@@ -1316,7 +1328,7 @@ class SalesOrderShipmentSerializer(NotesFieldMixin, InvenTreeModelSerializer):
         return queryset
 
     allocated_items = serializers.IntegerField(
-        read_only=True, label=_('Allocated Items')
+        read_only=True, allow_null=True, label=_('Allocated Items')
     )
 
     order_detail = SalesOrderSerializer(
@@ -1389,7 +1401,7 @@ class SalesOrderAllocationSerializer(InvenTreeModelSerializer):
     order = serializers.PrimaryKeyRelatedField(
         source='line.order', many=False, read_only=True
     )
-    serial = serializers.CharField(source='get_serial', read_only=True)
+    serial = serializers.CharField(source='get_serial', read_only=True, allow_null=True)
     quantity = serializers.FloatField(read_only=False)
     location = serializers.PrimaryKeyRelatedField(
         source='item.location', many=False, read_only=True
diff --git a/src/backend/InvenTree/part/serializers.py b/src/backend/InvenTree/part/serializers.py
index 5c8b4870ca..1522304d7a 100644
--- a/src/backend/InvenTree/part/serializers.py
+++ b/src/backend/InvenTree/part/serializers.py
@@ -126,9 +126,13 @@ class CategorySerializer(
         help_text=_('Parent part category'),
     )
 
-    part_count = serializers.IntegerField(read_only=True, label=_('Parts'))
+    part_count = serializers.IntegerField(
+        read_only=True, allow_null=True, label=_('Parts')
+    )
 
-    subcategories = serializers.IntegerField(read_only=True, label=_('Subcategories'))
+    subcategories = serializers.IntegerField(
+        read_only=True, allow_null=True, label=_('Subcategories')
+    )
 
     level = serializers.IntegerField(read_only=True)
 
@@ -149,7 +153,7 @@ class CategorySerializer(
         max_length=100,
     )
 
-    parent_default_location = serializers.IntegerField(read_only=True)
+    parent_default_location = serializers.IntegerField(read_only=True, allow_null=True)
 
 
 class CategoryTree(InvenTree.serializers.InvenTreeModelSerializer):
@@ -335,6 +339,7 @@ class PartParameterTemplateSerializer(
 
     parts = serializers.IntegerField(
         read_only=True,
+        allow_null=True,
         label=_('Parts'),
         help_text=_('Number of parts using this template'),
     )
@@ -396,7 +401,9 @@ class PartBriefSerializer(InvenTree.serializers.InvenTreeModelSerializer):
         read_only=True, allow_null=True
     )
 
-    image = InvenTree.serializers.InvenTreeImageSerializerField(read_only=True)
+    image = InvenTree.serializers.InvenTreeImageSerializerField(
+        read_only=True, allow_null=True
+    )
     thumbnail = serializers.CharField(source='get_thumbnail_url', read_only=True)
 
     IPN = serializers.CharField(
@@ -924,25 +931,47 @@ class PartSerializer(
     )
 
     # Annotated fields
-    allocated_to_build_orders = serializers.FloatField(read_only=True)
-    allocated_to_sales_orders = serializers.FloatField(read_only=True)
-    building = serializers.FloatField(read_only=True, label=_('Building'))
-    in_stock = serializers.FloatField(read_only=True, label=_('In Stock'))
-    ordering = serializers.FloatField(read_only=True, label=_('On Order'))
-    required_for_build_orders = serializers.IntegerField(read_only=True)
-    required_for_sales_orders = serializers.IntegerField(read_only=True)
-    stock_item_count = serializers.IntegerField(read_only=True, label=_('Stock Items'))
-    revision_count = serializers.IntegerField(read_only=True, label=_('Revisions'))
-    suppliers = serializers.IntegerField(read_only=True, label=_('Suppliers'))
-    total_in_stock = serializers.FloatField(read_only=True, label=_('Total Stock'))
-    external_stock = serializers.FloatField(read_only=True, label=_('External Stock'))
+    allocated_to_build_orders = serializers.FloatField(read_only=True, allow_null=True)
+    allocated_to_sales_orders = serializers.FloatField(read_only=True, allow_null=True)
+    building = serializers.FloatField(
+        read_only=True, allow_null=True, label=_('Building')
+    )
+    in_stock = serializers.FloatField(
+        read_only=True, allow_null=True, label=_('In Stock')
+    )
+    ordering = serializers.FloatField(
+        read_only=True, allow_null=True, label=_('On Order')
+    )
+    required_for_build_orders = serializers.IntegerField(
+        read_only=True, allow_null=True
+    )
+    required_for_sales_orders = serializers.IntegerField(
+        read_only=True, allow_null=True
+    )
+    stock_item_count = serializers.IntegerField(
+        read_only=True, allow_null=True, label=_('Stock Items')
+    )
+    revision_count = serializers.IntegerField(
+        read_only=True, allow_null=True, label=_('Revisions')
+    )
+    suppliers = serializers.IntegerField(
+        read_only=True, allow_null=True, label=_('Suppliers')
+    )
+    total_in_stock = serializers.FloatField(
+        read_only=True, allow_null=True, label=_('Total Stock')
+    )
+    external_stock = serializers.FloatField(
+        read_only=True, allow_null=True, label=_('External Stock')
+    )
     unallocated_stock = serializers.FloatField(
-        read_only=True, label=_('Unallocated Stock')
+        read_only=True, allow_null=True, label=_('Unallocated Stock')
     )
     category_default_location = serializers.IntegerField(
         read_only=True, allow_null=True
     )
-    variant_stock = serializers.FloatField(read_only=True, label=_('Variant Stock'))
+    variant_stock = serializers.FloatField(
+        read_only=True, allow_null=True, label=_('Variant Stock')
+    )
 
     minimum_stock = serializers.FloatField(
         required=False, label=_('Minimum Stock'), default=0
@@ -1657,11 +1686,17 @@ class BomItemSerializer(
         allow_null=True,
     )
 
-    on_order = serializers.FloatField(label=_('On Order'), read_only=True)
+    on_order = serializers.FloatField(
+        label=_('On Order'), read_only=True, allow_null=True
+    )
 
-    building = serializers.FloatField(label=_('In Production'), read_only=True)
+    building = serializers.FloatField(
+        label=_('In Production'), read_only=True, allow_null=True
+    )
 
-    can_build = serializers.FloatField(label=_('Can Build'), read_only=True)
+    can_build = serializers.FloatField(
+        label=_('Can Build'), read_only=True, allow_null=True
+    )
 
     # Cached pricing fields
     pricing_min = InvenTree.serializers.InvenTreeMoneySerializer(
@@ -1684,12 +1719,14 @@ class BomItemSerializer(
     )
 
     # Annotated fields for available stock
-    available_stock = serializers.FloatField(label=_('Available Stock'), read_only=True)
+    available_stock = serializers.FloatField(
+        label=_('Available Stock'), read_only=True, allow_null=True
+    )
 
-    available_substitute_stock = serializers.FloatField(read_only=True)
-    available_variant_stock = serializers.FloatField(read_only=True)
+    available_substitute_stock = serializers.FloatField(read_only=True, allow_null=True)
+    available_variant_stock = serializers.FloatField(read_only=True, allow_null=True)
 
-    external_stock = serializers.FloatField(read_only=True)
+    external_stock = serializers.FloatField(read_only=True, allow_null=True)
 
     @staticmethod
     def annotate_queryset(queryset):
diff --git a/src/backend/InvenTree/stock/serializers.py b/src/backend/InvenTree/stock/serializers.py
index 8a82328a54..2c6b838394 100644
--- a/src/backend/InvenTree/stock/serializers.py
+++ b/src/backend/InvenTree/stock/serializers.py
@@ -655,20 +655,20 @@ class StockItemSerializer(
 
     # Annotated fields
     allocated = serializers.FloatField(
-        required=False, read_only=True, label=_('Allocated Quantity')
+        read_only=True, allow_null=True, label=_('Allocated Quantity')
     )
     expired = serializers.BooleanField(
-        required=False, read_only=True, label=_('Expired')
+        read_only=True, allow_null=True, label=_('Expired')
     )
     installed_items = serializers.IntegerField(
-        read_only=True, required=False, label=_('Installed Items')
+        read_only=True, allow_null=True, label=_('Installed Items')
     )
     child_items = serializers.IntegerField(
-        read_only=True, required=False, label=_('Child Items')
+        read_only=True, allow_null=True, label=_('Child Items')
     )
-    stale = serializers.BooleanField(required=False, read_only=True, label=_('Stale'))
+    stale = serializers.BooleanField(read_only=True, allow_null=True, label=_('Stale'))
     tracking_items = serializers.IntegerField(
-        read_only=True, required=False, label=_('Tracking Items')
+        read_only=True, allow_null=True, label=_('Tracking Items')
     )
 
     purchase_price = InvenTree.serializers.InvenTreeMoneySerializer(
@@ -1161,7 +1161,7 @@ class StockLocationTypeSerializer(InvenTree.serializers.InvenTreeModelSerializer
 
         read_only_fields = ['location_count']
 
-    location_count = serializers.IntegerField(read_only=True)
+    location_count = serializers.IntegerField(read_only=True, allow_null=True)
 
     @staticmethod
     def annotate_queryset(queryset):
@@ -1273,7 +1273,7 @@ class LocationSerializer(
 
     # Detail for location type
     location_type_detail = StockLocationTypeSerializer(
-        source='location_type', read_only=True, many=False
+        source='location_type', read_only=True, allow_null=True, many=False
     )
 
 
diff --git a/src/backend/InvenTree/users/serializers.py b/src/backend/InvenTree/users/serializers.py
index 69ded40739..5950fb286d 100644
--- a/src/backend/InvenTree/users/serializers.py
+++ b/src/backend/InvenTree/users/serializers.py
@@ -283,9 +283,13 @@ class GroupSerializer(InvenTreeModelSerializer):
         """Return a list of permissions associated with the group."""
         return generate_permission_dict(group.permissions.all())
 
-    roles = RuleSetSerializer(source='rule_sets', many=True, read_only=True)
+    roles = RuleSetSerializer(
+        source='rule_sets', many=True, read_only=True, allow_null=True
+    )
 
-    users = UserSerializer(source='user_set', many=True, read_only=True)
+    users = UserSerializer(
+        source='user_set', many=True, read_only=True, allow_null=True
+    )
 
 
 class ExtendedUserSerializer(UserSerializer):