Catch AssertionError's in signals. Handle accordingly

netbox/dcim/models/cables.py

@@ -478,8 +478,11 @@ class CablePath(models.Model):
         Cable or WirelessLink connects (interfaces, console ports, circuit termination, etc.). All terminations must be
         of the same type and must belong to the same parent object.
         """
+        import logging
         from circuits.models import CircuitTermination
 
+        logger = logging.getLogger('netbox.dcim.cablepath')
+
         if not terminations:
             return None
 
@@ -558,6 +561,7 @@ class CablePath(models.Model):
                     pk__in=[t.rear_port_id for t in remote_terminations]
                 )
                 if len(rear_ports) > 1:
+                    logger.warning(f'All rear-port positions do not match.  Cannot continue path trace.')
                     assert all(rp.positions == 1 for rp in rear_ports)
                 elif rear_ports[0].positions > 1:
                     position_stack.append([fp.rear_port_position for fp in remote_terminations])

netbox/dcim/signals.py

@@ -95,7 +95,11 @@ def update_connected_endpoints(instance, created, raw=False, **kwargs):
             if not nodes:
                 continue
             if isinstance(nodes[0], PathEndpoint):
-                create_cablepath(nodes)
+                try:
+                    create_cablepath(nodes)
+                except AssertionError:
+                    # This is likely an unsupported path.  Catch the assertion error and don't save the path
+                    logger.error(f'Unsupported path from nodes: {[node.name for node in nodes].join(",")}')
             else:
                 rebuild_paths(nodes)
 

netbox/dcim/utils.py

@@ -49,12 +49,20 @@ def rebuild_paths(terminations):
     """
     Rebuild all CablePaths which traverse the specified nodes.
     """
+    import logging
     from dcim.models import CablePath
 
+    logger = logging.getLogger('netbox.dcim.cable')
+
     for obj in terminations:
         cable_paths = CablePath.objects.filter(_nodes__contains=obj)
 
         with transaction.atomic():
             for cp in cable_paths:
                 cp.delete()
-                create_cablepath(cp.origins)
+                try:
+                    create_cablepath(cp.origins)
+                except AssertionError:
+                    # This is likely an unsupported path.  Catch the assertion error and don't save the path
+                    logger.error(f'Unsupported path from cable path: {cp._nodes}')
+                    pass