diff --git a/ironic/api/controllers/v1/chassis.py b/ironic/api/controllers/v1/chassis.py
index df5f9df78d..4c5ffe5e3a 100644
--- a/ironic/api/controllers/v1/chassis.py
+++ b/ironic/api/controllers/v1/chassis.py
@@ -222,7 +222,7 @@ class ChassisController(rest.RestController):
         # /detail should only work against collections
         parent = pecan.request.path.split('/')[:-1][-1]
         if parent != "chassis":
-            raise exception.HTTPNotFound
+            raise exception.HTTPNotFound()
 
         resource_url = '/'.join(['chassis', 'detail'])
         return self._get_chassis_collection(marker, limit, sort_key, sort_dir,
diff --git a/ironic/api/controllers/v1/node.py b/ironic/api/controllers/v1/node.py
index 97796183fb..c34cfc1ec5 100644
--- a/ironic/api/controllers/v1/node.py
+++ b/ironic/api/controllers/v1/node.py
@@ -1168,7 +1168,7 @@ class NodesController(rest.RestController):
         # /detail should only work against collections
         parent = pecan.request.path.split('/')[:-1][-1]
         if parent != "nodes":
-            raise exception.HTTPNotFound
+            raise exception.HTTPNotFound()
 
         resource_url = '/'.join(['nodes', 'detail'])
         return self._get_nodes_collection(chassis_uuid, instance_uuid,
@@ -1209,7 +1209,7 @@ class NodesController(rest.RestController):
             of the resource to be returned.
         """
         if self.from_chassis:
-            raise exception.OperationNotPermitted
+            raise exception.OperationNotPermitted()
 
         api_utils.check_allow_specify_fields(fields)
 
@@ -1223,7 +1223,7 @@ class NodesController(rest.RestController):
         :param node: a node within the request body.
         """
         if self.from_chassis:
-            raise exception.OperationNotPermitted
+            raise exception.OperationNotPermitted()
 
         # NOTE(deva): get_topic_for checks if node.driver is in the hash ring
         #             and raises NoValidHost if it is not.
@@ -1262,7 +1262,7 @@ class NodesController(rest.RestController):
         :param patch: a json PATCH document to apply to this node.
         """
         if self.from_chassis:
-            raise exception.OperationNotPermitted
+            raise exception.OperationNotPermitted()
 
         rpc_node = api_utils.get_rpc_node(node_ident)
 
@@ -1333,7 +1333,7 @@ class NodesController(rest.RestController):
         :param node_ident: UUID or logical name of a node.
         """
         if self.from_chassis:
-            raise exception.OperationNotPermitted
+            raise exception.OperationNotPermitted()
 
         rpc_node = api_utils.get_rpc_node(node_ident)
 
diff --git a/ironic/api/controllers/v1/port.py b/ironic/api/controllers/v1/port.py
index 962d03bc56..e8f3abc14e 100644
--- a/ironic/api/controllers/v1/port.py
+++ b/ironic/api/controllers/v1/port.py
@@ -317,7 +317,7 @@ class PortsController(rest.RestController):
         # NOTE(lucasagomes): /detail should only work against collections
         parent = pecan.request.path.split('/')[:-1][-1]
         if parent != "ports":
-            raise exception.HTTPNotFound
+            raise exception.HTTPNotFound()
 
         resource_url = '/'.join(['ports', 'detail'])
         return self._get_ports_collection(node_uuid or node, address, marker,
@@ -333,7 +333,7 @@ class PortsController(rest.RestController):
             of the resource to be returned.
         """
         if self.from_nodes:
-            raise exception.OperationNotPermitted
+            raise exception.OperationNotPermitted()
 
         api_utils.check_allow_specify_fields(fields)
 
@@ -347,7 +347,7 @@ class PortsController(rest.RestController):
         :param port: a port within the request body.
         """
         if self.from_nodes:
-            raise exception.OperationNotPermitted
+            raise exception.OperationNotPermitted()
 
         new_port = objects.Port(pecan.request.context,
                                 **port.as_dict())
@@ -365,7 +365,7 @@ class PortsController(rest.RestController):
         :param patch: a json PATCH document to apply to this port.
         """
         if self.from_nodes:
-            raise exception.OperationNotPermitted
+            raise exception.OperationNotPermitted()
 
         rpc_port = objects.Port.get_by_uuid(pecan.request.context, port_uuid)
         try:
@@ -407,7 +407,7 @@ class PortsController(rest.RestController):
         :param port_uuid: UUID of a port.
         """
         if self.from_nodes:
-            raise exception.OperationNotPermitted
+            raise exception.OperationNotPermitted()
         rpc_port = objects.Port.get_by_uuid(pecan.request.context,
                                             port_uuid)
         rpc_node = objects.Node.get_by_id(pecan.request.context,