diff --git a/dnet-ariadneplus-graphdb-publisher/src/main/java/eu/dnetlib/ariadneplus/reader/json/ParseRDFJSON.java b/dnet-ariadneplus-graphdb-publisher/src/main/java/eu/dnetlib/ariadneplus/reader/json/ParseRDFJSON.java
index 5c0cacb..b04b686 100644
--- a/dnet-ariadneplus-graphdb-publisher/src/main/java/eu/dnetlib/ariadneplus/reader/json/ParseRDFJSON.java
+++ b/dnet-ariadneplus-graphdb-publisher/src/main/java/eu/dnetlib/ariadneplus/reader/json/ParseRDFJSON.java
@@ -67,6 +67,7 @@ public class ParseRDFJSON {
     }
 
     public boolean hasNextElement(){
+        if(it == null) return false;
         return it.hasNext();
     }