Index: trunk/src/org/openstreetmap/josm/actions/MergeNodesAction.java
===================================================================
--- trunk/src/org/openstreetmap/josm/actions/MergeNodesAction.java	(revision 12973)
+++ trunk/src/org/openstreetmap/josm/actions/MergeNodesAction.java	(revision 12974)
@@ -76,4 +76,5 @@
         Collection<OsmPrimitive> selection = getLayerManager().getEditDataSet().getAllSelected();
         List<Node> selectedNodes = OsmPrimitive.getFilteredList(selection, Node.class);
+        selectedNodes.removeIf(n -> n.isDeleted() || n.isIncomplete());
 
         if (selectedNodes.size() == 1) {