Index: C:/Dokumente und Einstellungen/kiehl/Eigene Dateien/Entwicklung/java/jackrabbit-original/jackrabbit-core/src/main/java/org/apache/jackrabbit/core/ItemImpl.java
===================================================================
--- C:/Dokumente und Einstellungen/kiehl/Eigene Dateien/Entwicklung/java/jackrabbit-original/jackrabbit-core/src/main/java/org/apache/jackrabbit/core/ItemImpl.java	(revision 514641)
+++ C:/Dokumente und Einstellungen/kiehl/Eigene Dateien/Entwicklung/java/jackrabbit-original/jackrabbit-core/src/main/java/org/apache/jackrabbit/core/ItemImpl.java	(working copy)
@@ -585,6 +585,7 @@
                                 && def.getRequiredType() == PropertyType.REFERENCE) {
                             for (int i = 0; i < values.length; i++) {
                                 boolean satisfied = false;
+                                String constraintViolationMsg = null;
                                 try {
                                     UUID targetUUID = (UUID) values[i].internalValue();
                                     Node targetNode = session.getNodeByUUID(targetUUID);
@@ -604,6 +605,22 @@
                                             break;
                                         }
                                     }
+                                    if (!satisfied) {
+                                    	NodeType[] mixinNodeTypes = targetNode.getMixinNodeTypes();
+                                        String[] targetMixins = new String[mixinNodeTypes.length];
+                                        for (int j = 0; j < mixinNodeTypes.length; j++) {
+                                            targetMixins[j] = mixinNodeTypes[j].getName();
+                                        }
+                                        String targetMixinsString = join(targetMixins);
+                                        String constraintsString = join(constraints);
+                                        constraintViolationMsg = prop.safeGetJCRPath()
+                                                + ": is constraint to ["
+                                                + constraintsString
+                                                + "] but references [primaryType='"
+                                                + targetNode.getPrimaryNodeType().getName()
+                                                + "', mixins="
+                                                + targetMixinsString + "]";
+                                    }
                                 } catch (RepositoryException re) {
                                     String msg = prop.safeGetJCRPath()
                                             + ": failed to check REFERENCE value constraint";
@@ -611,11 +628,8 @@
                                     throw new ConstraintViolationException(msg, re);
                                 }
                                 if (!satisfied) {
-                                    String msg = prop.safeGetJCRPath()
-                                            + ": does not satisfy the value constraint "
-                                            + constraints[0];   // just report the 1st
-                                    log.debug(msg);
-                                    throw new ConstraintViolationException(msg);
+                                    log.debug(constraintViolationMsg);
+                                    throw new ConstraintViolationException(constraintViolationMsg);
                                 }
                             }
                         }
@@ -643,6 +657,17 @@
         }
     }
 
+    private String join(String[] array) {
+        String constraintsString = "";
+        for (int j = 0; j < array.length; j++) {
+            if (j > 0) {
+                constraintsString += ", ";
+            }
+            constraintsString += "'" + array[j] + "'";
+        }
+        return constraintsString;
+    }
+
     private void removeTransientItems(Iterator iter) {
 
         /**