diff --git a/meshroom/core/attribute.py b/meshroom/core/attribute.py
index e0d71cd339..043804fba4 100644
--- a/meshroom/core/attribute.py
+++ b/meshroom/core/attribute.py
@@ -92,7 +92,8 @@ def getFullNameToNode(self):
 
     def getFullNameToGraph(self):
         """ Name inside the Graph: graphName.nodeName.groupName.name """
-        return '{}.{}'.format(self.node.graph.name, self.getFullNameToNode())
+        graphName = self.node.graph.name if self.node.graph else "UNDEFINED"
+        return '{}.{}'.format(graphName, self.getFullNameToNode())
 
     def asLinkExpr(self):
         """ Return link expression for this Attribute """
@@ -124,7 +125,8 @@ def getFullLabelToNode(self):
 
     def getFullLabelToGraph(self):
         """ Label inside the Graph: graphName nodeLabel groupLabel Label """
-        return '{} {}'.format(self.node.graph.name, self.getFullLabelToNode())
+        graphName = self.node.graph.name if self.node.graph else "UNDEFINED"
+        return '{} {}'.format(graphName, self.getFullLabelToNode())
 
     def getEnabled(self):
         if isinstance(self.desc.enabled, types.FunctionType):
diff --git a/meshroom/ui/qml/Viewer/Viewer2D.qml b/meshroom/ui/qml/Viewer/Viewer2D.qml
index 3829648d32..27b98d2f58 100644
--- a/meshroom/ui/qml/Viewer/Viewer2D.qml
+++ b/meshroom/ui/qml/Viewer/Viewer2D.qml
@@ -1003,9 +1003,9 @@ FocusScope {
                                 {
                                     return true;
                                 }
-                                var inputAttr = activeNode.attribute("input");
-                                if(!inputAttr)
+                                if(!activeNode.hasAttribute("input"))
                                     return false;
+                                var inputAttr = activeNode.attribute("input");
                                 var inputAttrLink = inputAttr.rootLinkParam;
                                 if(!inputAttrLink)
                                     return false;