diff --git a/build.properties b/build.properties
index 6aa6c2d48..d9680aabc 100644
--- a/build.properties
+++ b/build.properties
@@ -3,7 +3,7 @@ javacSource=1.4
 javacTarget=1.4
 
 # Release Configuration
-releaseVersion=0.487
+releaseVersion=0.488
 releaseFile=yacy_dev_v${releaseVersion}_${DSTAMP}_${releaseNr}.tar.gz
 #releaseFile=yacy_v${releaseVersion}_${DSTAMP}_${releaseNr}.tar.gz
 releaseDir=yacy_dev_v${releaseVersion}_${DSTAMP}_${releaseNr}
diff --git a/source/de/anomic/index/indexRWIEntryNew.java b/source/de/anomic/index/indexRWIEntryNew.java
index 8d857093d..dc2efb9b0 100644
--- a/source/de/anomic/index/indexRWIEntryNew.java
+++ b/source/de/anomic/index/indexRWIEntryNew.java
@@ -149,6 +149,7 @@ public class indexRWIEntryNew  implements Cloneable, indexRWIEntry {
     }
 
     public indexRWIEntryNew(indexRWIEntryOld oldEntry) {
+        assert oldEntry.urlHash() != null;
         this.entry = urlEntryRow.newEntry();
         int mddlm = plasmaWordIndex.microDateDays(oldEntry.lastModified());
         int mddct = plasmaWordIndex.microDateDays(System.currentTimeMillis());
diff --git a/source/de/anomic/index/indexRWIEntryOld.java b/source/de/anomic/index/indexRWIEntryOld.java
index a0010f84b..cb090d988 100644
--- a/source/de/anomic/index/indexRWIEntryOld.java
+++ b/source/de/anomic/index/indexRWIEntryOld.java
@@ -99,6 +99,7 @@ public class indexRWIEntryOld implements Cloneable, indexRWIEntry {
         // more needed attributes:
         // - boolean: appearance attributes: title, appears in header, anchor-descr, image-tag, hervorhebungen, meta-tags, word in link etc
         // - boolean: URL attributes
+        assert (urlHash != null);
         assert (urlHash.length() == 12) : "urlhash = " + urlHash;
         if ((language == null) || (language.length() != urlEntryRow.width(col_language))) language = "uk";
         this.entry = urlEntryRow.newEntry();
diff --git a/source/de/anomic/plasma/plasmaWordIndex.java b/source/de/anomic/plasma/plasmaWordIndex.java
index 35d7220b6..f51036c03 100644
--- a/source/de/anomic/plasma/plasmaWordIndex.java
+++ b/source/de/anomic/plasma/plasmaWordIndex.java
@@ -239,8 +239,11 @@ public final class plasmaWordIndex implements indexRI {
     }
 
     public indexContainer addEntry(String wordHash, indexRWIEntry entry, long updateTime, boolean dhtInCase) {
-        if ((useCollectionIndex) && (entry instanceof indexRWIEntryOld)) entry = new indexRWIEntryNew((indexRWIEntryOld) entry);
-        
+        if ((useCollectionIndex) && (entry instanceof indexRWIEntryOld)) {
+            if (entry.urlHash() == null) return null;
+            entry = new indexRWIEntryNew((indexRWIEntryOld) entry);
+        }
+
         // set dhtInCase depending on wordHash
         if ((!dhtInCase) && (yacyDHTAction.shallBeOwnWord(wordHash))) dhtInCase = true;
         
@@ -261,7 +264,9 @@ public final class plasmaWordIndex implements indexRI {
         indexRWIEntryOld old;
         while (i.hasNext()) {
             old = (indexRWIEntryOld) i.next();
-            newentries.add(new indexRWIEntryNew(old));
+            if (old.urlHash() != null) {
+                newentries.add(new indexRWIEntryNew(old));
+            }
         }
         return newentries;
     }
diff --git a/source/de/anomic/yacy/yacyClient.java b/source/de/anomic/yacy/yacyClient.java
index 69afaa936..20d0f1470 100644
--- a/source/de/anomic/yacy/yacyClient.java
+++ b/source/de/anomic/yacy/yacyClient.java
@@ -553,6 +553,7 @@ public final class yacyClient {
                 // add the url entry to the word indexes
                 for (int m = 0; m < words; m++) {
                     if ((wordIndex.useCollectionIndex) && (entry instanceof indexRWIEntryOld)) {
+                        if (entry.urlHash() == null) continue; 
                         entry = new indexRWIEntryNew((indexRWIEntryOld) entry);
                     }
                     container[m].add(new indexRWIEntry[]{entry}, System.currentTimeMillis());