diff --git a/meshroom/ui/graph.py b/meshroom/ui/graph.py
index 0183828c..8883f2cf 100644
--- a/meshroom/ui/graph.py
+++ b/meshroom/ui/graph.py
@@ -753,6 +753,8 @@ class UIGraph(QObject):
     def canExpandForLoop(self, currentEdge):
         """ Check if the list attribute can be expanded by looking at all the edges connected to it. """
         listAttribute = currentEdge.src.root
+        if not listAttribute:
+            return False
         srcIndex = listAttribute.index(currentEdge.src)
         allSrc = [e.src for e in self._graph.edges.values()]
         for i in range(len(listAttribute)):