diff --git a/kapital_bank/bank_api.py b/kapital_bank/bank_api.py
index 625ee3a..0a56b27 100644
--- a/kapital_bank/bank_api.py
+++ b/kapital_bank/bank_api.py
@@ -658,15 +658,19 @@ def create_unmapped_customers(settings_name=None):
         if not unmapped:
             return {"success": True, "created_count": 0, "message": "No unmapped customers in table to create"}
 
-        # Validate config upfront — clearer than ERPNext's cryptic
-        # "Could not find Customer Group" thrown deep inside party creation.
+        # Validate config upfront — clearer than ERPNext's errors thrown deep inside
+        # party creation ("Could not find Customer Group" / "Cannot select a Group type").
         for mapping, _kb_customer in unmapped:
             group = mapping.customer_group or doc.default_customer_group
             if not group or not frappe.db.exists("Customer Group", group):
                 return {"success": False, "message": "Set a Default Customer Group on Kapital Bank Settings (or a Customer Group on each customer mapping row) before creating customers."}
+            if frappe.db.get_value("Customer Group", group, "is_group"):
+                return {"success": False, "message": f"Customer Group '{group}' is a group node — pick a leaf (non-group) Customer Group."}
             territory = mapping.territory or doc.default_territory
             if not territory or not frappe.db.exists("Territory", territory):
                 return {"success": False, "message": "Set a Default Territory on Kapital Bank Settings (or a Territory on each customer mapping row) before creating customers."}
+            if frappe.db.get_value("Territory", territory, "is_group"):
+                return {"success": False, "message": f"Territory '{territory}' is a group node — pick a leaf (non-group) Territory."}
 
         created = 0
         for mapping, kb_customer in unmapped:
@@ -739,6 +743,8 @@ def create_unmapped_suppliers(settings_name=None):
             group = mapping.supplier_group or doc.default_supplier_group
             if not group or not frappe.db.exists("Supplier Group", group):
                 return {"success": False, "message": "Set a Default Supplier Group on Kapital Bank Settings (or a Supplier Group on each supplier mapping row) before creating suppliers."}
+            if frappe.db.get_value("Supplier Group", group, "is_group"):
+                return {"success": False, "message": f"Supplier Group '{group}' is a group node — pick a leaf (non-group) Supplier Group."}
 
         created = 0
         for mapping, kb_supplier in unmapped: