diff --git a/myems-api/core/contact.py b/myems-api/core/contact.py
index 3ba6ed47..7166f0c5 100644
--- a/myems-api/core/contact.py
+++ b/myems-api/core/contact.py
@@ -94,7 +94,7 @@ class ContactCollection:
         if cursor.fetchone() is not None:
             cursor.close()
             cnx.disconnect()
-            raise falcon.HTTPError(falcon.HTTP_404, title='API.BAD_REQUEST',
+            raise falcon.HTTPError(falcon.HTTP_400, title='API.BAD_REQUEST',
                                    description='API.CONTACT_NAME_IS_ALREADY_IN_USE')
 
         add_row = (" INSERT INTO tbl_contacts "
@@ -292,7 +292,7 @@ class ContactItem:
         if cursor.fetchone() is not None:
             cursor.close()
             cnx.disconnect()
-            raise falcon.HTTPError(falcon.HTTP_404, title='API.BAD_REQUEST',
+            raise falcon.HTTPError(falcon.HTTP_400, title='API.BAD_REQUEST',
                                    description='API.CONTACT_NAME_IS_ALREADY_IN_USE')
 
         update_row = (" UPDATE tbl_contacts "
diff --git a/myems-api/core/equipment.py b/myems-api/core/equipment.py
index 5d7e51aa..71728a5b 100644
--- a/myems-api/core/equipment.py
+++ b/myems-api/core/equipment.py
@@ -108,7 +108,7 @@ class EquipmentCollection:
         if cursor.fetchone() is not None:
             cursor.close()
             cnx.disconnect()
-            raise falcon.HTTPError(falcon.HTTP_404, title='API.BAD_REQUEST',
+            raise falcon.HTTPError(falcon.HTTP_400, title='API.BAD_REQUEST',
                                    description='API.EQUIPMENT_NAME_IS_ALREADY_IN_USE')
 
         if cost_center_id is not None:
diff --git a/myems-api/core/gateway.py b/myems-api/core/gateway.py
index 26899690..3a937eeb 100644
--- a/myems-api/core/gateway.py
+++ b/myems-api/core/gateway.py
@@ -67,7 +67,7 @@ class GatewayCollection:
         if cursor.fetchone() is not None:
             cursor.close()
             cnx.disconnect()
-            raise falcon.HTTPError(falcon.HTTP_404, title='API.BAD_REQUEST',
+            raise falcon.HTTPError(falcon.HTTP_400, title='API.BAD_REQUEST',
                                    description='API.GATEWAY_NAME_IS_ALREADY_IN_USE')
 
         add_values = (" INSERT INTO tbl_gateways (name, uuid, token) "
@@ -200,7 +200,7 @@ class GatewayItem:
         if cursor.fetchone() is not None:
             cursor.close()
             cnx.disconnect()
-            raise falcon.HTTPError(falcon.HTTP_404, title='API.BAD_REQUEST',
+            raise falcon.HTTPError(falcon.HTTP_400, title='API.BAD_REQUEST',
                                    description='API.GATEWAY_NAME_IS_ALREADY_IN_USE')
 
         update_row = (" UPDATE tbl_gateways "
diff --git a/myems-api/core/notification.py b/myems-api/core/notification.py
index 6db5aa54..31d7e77b 100644
--- a/myems-api/core/notification.py
+++ b/myems-api/core/notification.py
@@ -22,7 +22,8 @@ class NotificationCollection:
         if status is not None:
             status = str.strip(status)
             if status not in ['unread', 'read', 'archived']:
-                raise falcon.HTTPError(falcon.HTTP_400, title='API.BAD_REQUEST', description='API.INVALID_STATUS')
+                raise falcon.HTTPError(falcon.HTTP_400, title='API.BAD_REQUEST',
+                                       description='API.INVALID_STATUS')
 
         timezone_offset = int(config.utc_offset[1:3]) * 60 + int(config.utc_offset[4:6])
         if config.utc_offset[0] == '-':
diff --git a/myems-api/core/storetype.py b/myems-api/core/storetype.py
index eb27f417..8063126d 100644
--- a/myems-api/core/storetype.py
+++ b/myems-api/core/storetype.py
@@ -79,7 +79,7 @@ class StoreTypeCollection:
         if cursor.fetchone() is not None:
             cursor.close()
             cnx.disconnect()
-            raise falcon.HTTPError(falcon.HTTP_404, title='API.BAD_REQUEST',
+            raise falcon.HTTPError(falcon.HTTP_400, title='API.BAD_REQUEST',
                                    description='API.STORE_TYPE_NAME_IS_ALREADY_IN_USE')
 
         cursor.execute(" SELECT simplified_code "
@@ -88,7 +88,7 @@ class StoreTypeCollection:
         if cursor.fetchone() is not None:
             cursor.close()
             cnx.disconnect()
-            raise falcon.HTTPError(falcon.HTTP_404, title='API.BAD_REQUEST',
+            raise falcon.HTTPError(falcon.HTTP_400, title='API.BAD_REQUEST',
                                    description='API.STORE_TYPE_SIMPLIFIED_CODE_IS_ALREADY_IN_USE')
 
         add_value = (" INSERT INTO tbl_store_types "
@@ -234,7 +234,7 @@ class StoreTypeItem:
         if cursor.fetchone() is not None:
             cursor.close()
             cnx.disconnect()
-            raise falcon.HTTPError(falcon.HTTP_404, title='API.BAD_REQUEST',
+            raise falcon.HTTPError(falcon.HTTP_400, title='API.BAD_REQUEST',
                                    description='API.STORE_TYPE_NAME_IS_ALREADY_IN_USE')
 
         cursor.execute(" SELECT simplified_code "
diff --git a/myems-api/core/tariff.py b/myems-api/core/tariff.py
index d1a32cd1..1948ede8 100644
--- a/myems-api/core/tariff.py
+++ b/myems-api/core/tariff.py
@@ -151,7 +151,7 @@ class TariffCollection:
         if cursor.fetchone() is not None:
             cursor.close()
             cnx.disconnect()
-            raise falcon.HTTPError(falcon.HTTP_404, title='API.BAD_REQUEST',
+            raise falcon.HTTPError(falcon.HTTP_400, title='API.BAD_REQUEST',
                                    description='API.TARIFF_NAME_IS_ALREADY_IN_USE')
 
         cursor.execute(" SELECT name "
@@ -427,7 +427,7 @@ class TariffItem:
         if cursor.fetchone() is not None:
             cursor.close()
             cnx.disconnect()
-            raise falcon.HTTPError(falcon.HTTP_404, title='API.BAD_REQUEST',
+            raise falcon.HTTPError(falcon.HTTP_400, title='API.BAD_REQUEST',
                                    description='API.TARIFF_NAME_IS_ALREADY_IN_USE')
 
         valid_from = datetime.strptime(new_values['data']['valid_from'], '%Y-%m-%dT%H:%M:%S')
diff --git a/myems-api/core/tenanttype.py b/myems-api/core/tenanttype.py
index 5fa96319..b423f282 100644
--- a/myems-api/core/tenanttype.py
+++ b/myems-api/core/tenanttype.py
@@ -79,7 +79,7 @@ class TenantTypeCollection:
         if cursor.fetchone() is not None:
             cursor.close()
             cnx.disconnect()
-            raise falcon.HTTPError(falcon.HTTP_404, title='API.BAD_REQUEST',
+            raise falcon.HTTPError(falcon.HTTP_400, title='API.BAD_REQUEST',
                                    description='API.TENANT_TYPE_NAME_IS_ALREADY_IN_USE')
 
         cursor.execute(" SELECT simplified_code "
@@ -88,7 +88,7 @@ class TenantTypeCollection:
         if cursor.fetchone() is not None:
             cursor.close()
             cnx.disconnect()
-            raise falcon.HTTPError(falcon.HTTP_404, title='API.BAD_REQUEST',
+            raise falcon.HTTPError(falcon.HTTP_400, title='API.BAD_REQUEST',
                                    description='API.TENANT_TYPE_SIMPLIFIED_CODE_IS_ALREADY_IN_USE')
 
         add_value = (" INSERT INTO tbl_tenant_types "
diff --git a/myems-api/core/virtualmeter.py b/myems-api/core/virtualmeter.py
index 1b6c15ec..cc811409 100644
--- a/myems-api/core/virtualmeter.py
+++ b/myems-api/core/virtualmeter.py
@@ -769,7 +769,7 @@ class VirtualMeterItem:
         if cursor.fetchone() is not None:
             cursor.close()
             cnx.disconnect()
-            raise falcon.HTTPError(falcon.HTTP_404, title='API.BAD_REQUEST',
+            raise falcon.HTTPError(falcon.HTTP_400, title='API.BAD_REQUEST',
                                    description='API.VIRTUAL_METER_NAME_IS_ALREADY_IN_USE')
 
         cursor.execute(" SELECT name "
@@ -808,7 +808,7 @@ class VirtualMeterItem:
                 if row[1] != energy_category_id:
                     cursor.close()
                     cnx.disconnect()
-                    raise falcon.HTTPError(falcon.HTTP_404, title='API.BAD_REQUEST',
+                    raise falcon.HTTPError(falcon.HTTP_400, title='API.BAD_REQUEST',
                                            description='API.ENERGY_ITEM_IS_NOT_BELONG_TO_ENERGY_CATEGORY')
 
         for variable in new_values['data']['expression']['variables']: