diff --git a/gns3server/handlers/api/compute/iou_handler.py b/gns3server/handlers/api/compute/iou_handler.py
index d6868647..029e8c27 100644
--- a/gns3server/handlers/api/compute/iou_handler.py
+++ b/gns3server/handlers/api/compute/iou_handler.py
@@ -407,6 +407,6 @@ class IOUHandler:
 
         # Raise error if user try to escape
         if filename[0] == ".":
-            raise aiohttp.web.HTTPForbidden
+            raise aiohttp.web.HTTPForbidden()
 
         yield from response.file(image_path)
diff --git a/gns3server/handlers/api/compute/project_handler.py b/gns3server/handlers/api/compute/project_handler.py
index fec5bf44..73662ca7 100644
--- a/gns3server/handlers/api/compute/project_handler.py
+++ b/gns3server/handlers/api/compute/project_handler.py
@@ -231,7 +231,7 @@ class ProjectHandler:
 
         # Raise error if user try to escape
         if path[0] == ".":
-            raise aiohttp.web.HTTPForbidden
+            raise aiohttp.web.HTTPForbidden()
         path = os.path.join(project.path, path)
 
         response.content_type = "application/octet-stream"
@@ -272,7 +272,7 @@ class ProjectHandler:
 
         # Raise an error if user try to escape
         if path[0] == ".":
-            raise aiohttp.web.HTTPForbidden
+            raise aiohttp.web.HTTPForbidden()
         path = os.path.join(project.path, path)
 
         response.content_type = "application/octet-stream"
@@ -314,7 +314,7 @@ class ProjectHandler:
 
         # Raise error if user try to escape
         if path[0] == ".":
-            raise aiohttp.web.HTTPForbidden
+            raise aiohttp.web.HTTPForbidden()
         path = os.path.join(project.path, path)
 
         response.set_status(200)
diff --git a/gns3server/handlers/api/compute/qemu_handler.py b/gns3server/handlers/api/compute/qemu_handler.py
index 44002196..129ac0d9 100644
--- a/gns3server/handlers/api/compute/qemu_handler.py
+++ b/gns3server/handlers/api/compute/qemu_handler.py
@@ -498,6 +498,6 @@ class QEMUHandler:
 
         # Raise error if user try to escape
         if filename[0] == ".":
-            raise aiohttp.web.HTTPForbidden
+            raise aiohttp.web.HTTPForbidden()
 
         yield from response.file(image_path)
diff --git a/gns3server/handlers/api/controller/node_handler.py b/gns3server/handlers/api/controller/node_handler.py
index 9424ea9b..808390ab 100644
--- a/gns3server/handlers/api/controller/node_handler.py
+++ b/gns3server/handlers/api/controller/node_handler.py
@@ -15,7 +15,6 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-import os
 import aiohttp
 
 from gns3server.web.route import Route
@@ -370,7 +369,7 @@ class NodeHandler:
 
         # Raise error if user try to escape
         if path[0] == ".":
-            raise aiohttp.web.HTTPForbidden
+            raise aiohttp.web.HTTPForbidden()
 
         node_type = node.node_type
         path = "/project-files/{}/{}/{}".format(node_type, node.id, path)
@@ -406,7 +405,7 @@ class NodeHandler:
 
         # Raise error if user try to escape
         if path[0] == ".":
-            raise aiohttp.web.HTTPForbidden
+            raise aiohttp.web.HTTPForbidden()
 
         node_type = node.node_type
         path = "/project-files/{}/{}/{}".format(node_type, node.id, path)
diff --git a/gns3server/handlers/api/controller/project_handler.py b/gns3server/handlers/api/controller/project_handler.py
index 82e29a57..8d7337dd 100644
--- a/gns3server/handlers/api/controller/project_handler.py
+++ b/gns3server/handlers/api/controller/project_handler.py
@@ -398,7 +398,7 @@ class ProjectHandler:
 
         # Raise error if user try to escape
         if path[0] == ".":
-            raise aiohttp.web.HTTPForbidden
+            raise aiohttp.web.HTTPForbidden()
         path = os.path.join(project.path, path)
 
         response.content_type = "application/octet-stream"
@@ -440,7 +440,7 @@ class ProjectHandler:
 
         # Raise error if user try to escape
         if path[0] == ".":
-            raise aiohttp.web.HTTPForbidden
+            raise aiohttp.web.HTTPForbidden()
         path = os.path.join(project.path, path)
 
         response.set_status(200)