diff --git a/gns3server/controller/link.py b/gns3server/controller/link.py
index b01490fa..a5421150 100644
--- a/gns3server/controller/link.py
+++ b/gns3server/controller/link.py
@@ -198,6 +198,8 @@ class Link:
         """
 
         port = node.get_port(adapter_number, port_number)
+        if port is None:
+            raise aiohttp.web.HTTPNotFound(text="Port {}/{} for {} not found".format(adapter_number, port_number, node.name))
         if port.link is not None:
             raise aiohttp.web.HTTPConflict(text="Port is already used")
 
@@ -213,6 +215,8 @@ class Link:
 
             # Check if user is not connecting serial => ethernet
             other_port = other_node["node"].get_port(other_node["adapter_number"], other_node["port_number"])
+            if other_port is None:
+                raise aiohttp.web.HTTPNotFound(text="Port {}/{} for {} not found".format(other_node["adapter_number"], other_node["port_number"], other_node["node"].name))
             if port.link_type != other_port.link_type:
                 raise aiohttp.web.HTTPConflict(text="It's not allowed to connect a {} to a {}".format(other_port.link_type, port.link_type))
 
diff --git a/gns3server/controller/node.py b/gns3server/controller/node.py
index 275b3c20..f960a8cf 100644
--- a/gns3server/controller/node.py
+++ b/gns3server/controller/node.py
@@ -574,12 +574,12 @@ class Node:
     def get_port(self, adapter_number, port_number):
         """
         Return the port for this adapter_number and port_number
-        or raise an HTTPNotFound
+        or returns None if the port is not found
         """
         for port in self.ports:
             if port.adapter_number == adapter_number and port.port_number == port_number:
                 return port
-        raise aiohttp.web.HTTPNotFound(text="Port {}/{} for {} not found".format(adapter_number, port_number, self.name))
+        return None
 
     def _list_ports(self):
         """
diff --git a/gns3server/controller/project.py b/gns3server/controller/project.py
index a0bd8209..7c8a11e0 100644
--- a/gns3server/controller/project.py
+++ b/gns3server/controller/project.py
@@ -783,8 +783,11 @@ class Project:
                 for node_link in link_data["nodes"]:
                     node = self.get_node(node_link["node_id"])
                     port = node.get_port(node_link["adapter_number"], node_link["port_number"])
+                    if port is None:
+                        log.warning("Port {}/{} for {} not found".format(node_link["adapter_number"], node_link["port_number"], node.name))
+                        continue
                     if port.link is not None:
-                        # the node port is already attached to another link
+                        log.warning("Port {}/{} is already connected to link ID {}".format(node_link["adapter_number"], node_link["port_number"], port.link.id))
                         continue
                     yield from link.add_node(node, node_link["adapter_number"], node_link["port_number"], label=node_link.get("label"), dump=False)
                 if len(link.nodes) != 2: