diff --git src/java/org/apache/nutch/crawl/GeneratorJob.java src/java/org/apache/nutch/crawl/GeneratorJob.java
index e249d26..c528008 100644
--- src/java/org/apache/nutch/crawl/GeneratorJob.java
+++ src/java/org/apache/nutch/crawl/GeneratorJob.java
@@ -234,6 +234,9 @@ public class GeneratorJob extends NutchTool implements Tool {
     long finish = System.currentTimeMillis();
     LOG.info("GeneratorJob: finished at " + sdf.format(finish) + ", time elapsed: " + TimingUtil.elapsedTime(start, finish));
     LOG.info("GeneratorJob: generated batch id: " + batchId + " containing " + GeneratorReducer.count + " URLs");
+    if (GeneratorReducer.count == 0) {
+      return null;
+    }
     return batchId;
   }