Index: trunk/src/org/openstreetmap/josm/actions/ValidateAction.java
===================================================================
--- trunk/src/org/openstreetmap/josm/actions/ValidateAction.java	(revision 14834)
+++ trunk/src/org/openstreetmap/josm/actions/ValidateAction.java	(revision 14835)
@@ -12,4 +12,5 @@
 import java.util.Optional;
 
+import org.openstreetmap.josm.data.osm.DataSet;
 import org.openstreetmap.josm.data.osm.OsmPrimitive;
 import org.openstreetmap.josm.data.preferences.sources.ValidatorPrefHelper;
@@ -95,5 +96,6 @@
     @Override
     public void updateEnabledState() {
-        setEnabled(getLayerManager().getActiveDataSet() != null);
+        DataSet ds = getLayerManager().getActiveDataSet() ;
+        setEnabled(ds != null && !ds.isEmpty());
     }
 
Index: trunk/src/org/openstreetmap/josm/data/osm/DataSet.java
===================================================================
--- trunk/src/org/openstreetmap/josm/data/osm/DataSet.java	(revision 14834)
+++ trunk/src/org/openstreetmap/josm/data/osm/DataSet.java	(revision 14835)
@@ -1201,3 +1201,11 @@
         this.remark = remark;
     }
+
+    /**
+     * @return true if this Dataset contains no primitives
+     * @since 14835
+     */
+    public boolean isEmpty() {
+        return allPrimitives.isEmpty();
+    }
 }