Index: jackrabbit-core/src/main/java/org/apache/jackrabbit/core/version/InternalVersionHistoryImpl.java
===================================================================
--- jackrabbit-core/src/main/java/org/apache/jackrabbit/core/version/InternalVersionHistoryImpl.java	(revision 1787004)
+++ jackrabbit-core/src/main/java/org/apache/jackrabbit/core/version/InternalVersionHistoryImpl.java	(working copy)
@@ -167,7 +167,7 @@
     // fix legacy
     private void fixLegacy() throws RepositoryException {
         if (rootVersion.getSuccessors().isEmpty()) {
-            for (Name versionName : nameCache.keySet()) {
+            for (Name versionName : getVersionNames()) {
                 InternalVersionImpl v = createVersionInstance(versionName);
                 v.legacyResolveSuccessors();
             }
Index: jackrabbit-core/src/main/java/org/apache/jackrabbit/core/version/InternalVersionImpl.java
===================================================================
--- jackrabbit-core/src/main/java/org/apache/jackrabbit/core/version/InternalVersionImpl.java	(revision 1787004)
+++ jackrabbit-core/src/main/java/org/apache/jackrabbit/core/version/InternalVersionImpl.java	(working copy)
@@ -441,7 +441,10 @@
             for (InternalValue value : values) {
                 InternalVersionImpl v = (InternalVersionImpl)
                         versionHistory.getVersion(value.getNodeId());
-                v.internalAddSuccessor(this, false);
+                // version may be null if history is broken
+                if (v != null) {
+                    v.internalAddSuccessor(this, false);
+                }
             }
         }
     }