diff --git a/service/api/src/main/java/org/eclipse/kapua/KapuaEntityUniquenessException.java b/service/api/src/main/java/org/eclipse/kapua/KapuaEntityUniquenessException.java
index c004fc61e98..b0ca64825da 100644
--- a/service/api/src/main/java/org/eclipse/kapua/KapuaEntityUniquenessException.java
+++ b/service/api/src/main/java/org/eclipse/kapua/KapuaEntityUniquenessException.java
@@ -24,6 +24,8 @@
  */
 public class KapuaEntityUniquenessException extends KapuaException {
 
+    private static final long serialVersionUID = -5398114226720500553L;
+
     private final String entityType;
     private final List<Map.Entry<String, Object>> uniquesFieldValues;
 
@@ -35,7 +37,7 @@ public class KapuaEntityUniquenessException extends KapuaException {
      * @since 1.0.0
      */
     public KapuaEntityUniquenessException(String entityType, List<Map.Entry<String, Object>> uniquesFieldValues) {
-        super(KapuaErrorCodes.ENTITY_UNIQUENESS, uniquesFieldValues);
+        super(KapuaErrorCodes.ENTITY_UNIQUENESS, entityType, uniquesFieldValues);
 
         this.entityType = entityType;
         this.uniquesFieldValues = uniquesFieldValues;
diff --git a/service/api/src/main/resources/kapua-service-error-messages.properties b/service/api/src/main/resources/kapua-service-error-messages.properties
index 2f73b408a01..dc85cfed465 100644
--- a/service/api/src/main/resources/kapua-service-error-messages.properties
+++ b/service/api/src/main/resources/kapua-service-error-messages.properties
@@ -20,6 +20,7 @@ ENTITY_CLONE_ERROR=Severe error while cloning: {0}
 ENTITY_NOT_FOUND=The entity of type {0} with id/name {1} was not found.
 ENTITY_PROPERTIES_READ_ERROR=Error while reading {0} from KapuaEntity. String-formatted value is: {1}
 ENTITY_PROPERTIES_WRITE_ERROR=Error while writing {0} to KapuaEntity. Properties are: {1}
+ENTITY_UNIQUENESS=Duplicate {0} entry for values: {1}
 EXTERNAL_ID_ALREADY_EXIST_IN_ANOTHER_ACCOUNT=An entity with the same external id {0} already exists in another account.
 ILLEGAL_ACCESS=The current subject is not authorized for {0}.
 ILLEGAL_ARGUMENT=An illegal value was provided for the argument {0}: {1}.
diff --git a/service/api/src/test/java/org/eclipse/kapua/KapuaEntityUniquenessExceptionTest.java b/service/api/src/test/java/org/eclipse/kapua/KapuaEntityUniquenessExceptionTest.java
index 6174b2426da..0806cf5eda6 100644
--- a/service/api/src/test/java/org/eclipse/kapua/KapuaEntityUniquenessExceptionTest.java
+++ b/service/api/src/test/java/org/eclipse/kapua/KapuaEntityUniquenessExceptionTest.java
@@ -17,66 +17,36 @@
 import org.junit.Before;
 import org.junit.Test;
 import org.junit.experimental.categories.Category;
-import org.mockito.Mockito;
 
+import java.util.AbstractMap;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 
-
-
 @Category(JUnitTests.class)
 public class KapuaEntityUniquenessExceptionTest {
 
     String[] entityType;
     List<Map.Entry<String, Object>> uniquesFieldValues;
-    Map.Entry mapEntry;
 
     @Before
     public void initialize() {
-        entityType = new String[]{"Entity Type", null};
+        entityType = new String[] { "AEntity", "AnotherEntity" };
         uniquesFieldValues = new LinkedList<>();
-        mapEntry = Mockito.mock(Map.Entry.class);
-        uniquesFieldValues.add(mapEntry);
-        uniquesFieldValues.add(mapEntry);
-        uniquesFieldValues.add(null);
-    }
 
-    @Test
-    public void kapuaEntityUniquenessExceptionTest() {
-        for (String type : entityType) {
-            KapuaEntityUniquenessException kapuaEntityUniquenessException1 = new KapuaEntityUniquenessException(type, uniquesFieldValues);
-            Assert.assertEquals("Expected and actual values should be the same.", type, kapuaEntityUniquenessException1.getEntityType());
-            Assert.assertEquals("Expected and actual values should be the same.", uniquesFieldValues, kapuaEntityUniquenessException1.getUniquesFieldValues());
-            Assert.assertEquals("Expected and actual values should be the same.", KapuaErrorCodes.ENTITY_UNIQUENESS, kapuaEntityUniquenessException1.getCode());
-            Assert.assertEquals("Expected and actual values should be the same.", "Error: " + uniquesFieldValues, kapuaEntityUniquenessException1.getMessage());
-            Assert.assertNull("Null expected.", kapuaEntityUniquenessException1.getCause());
-        }
+        uniquesFieldValues.add(new AbstractMap.SimpleEntry<>("aField", "aValue"));
+        uniquesFieldValues.add(new AbstractMap.SimpleEntry<>("anotherField", "anotherValue"));
     }
 
     @Test
-    public void kapuaEntityUniquenessExceptionNullFieldValuesTest() {
-        for (String type : entityType) {
-            KapuaEntityUniquenessException kapuaEntityUniquenessException2 = new KapuaEntityUniquenessException(type, null);
-            Assert.assertEquals("Expected and actual values should be the same.", type, kapuaEntityUniquenessException2.getEntityType());
-            Assert.assertNull("Null expected.", kapuaEntityUniquenessException2.getUniquesFieldValues());
-            Assert.assertEquals("Expected and actual values should be the same.", KapuaErrorCodes.ENTITY_UNIQUENESS, kapuaEntityUniquenessException2.getCode());
-            Assert.assertEquals("Expected and actual values should be the same.", "Error: null", kapuaEntityUniquenessException2.getMessage());
-            Assert.assertNull("Null expected.", kapuaEntityUniquenessException2.getCause());
-        }
-    }
-
-    @Test(expected = KapuaEntityUniquenessException.class)
-    public void throwingExceptionTest() throws KapuaEntityUniquenessException {
-        for (String type : entityType) {
-            throw new KapuaEntityUniquenessException(type, uniquesFieldValues);
-        }
-    }
-
-    @Test(expected = KapuaEntityUniquenessException.class)
-    public void throwingExceptionNullFieldValuesTest() throws KapuaEntityUniquenessException {
+    public void kapuaEntityUniquenessExceptionTest() {
         for (String type : entityType) {
-            throw new KapuaEntityUniquenessException(type, null);
+            KapuaEntityUniquenessException kapuaEntityUniquenessException = new KapuaEntityUniquenessException(type, uniquesFieldValues);
+            Assert.assertEquals(type, kapuaEntityUniquenessException.getEntityType());
+            Assert.assertEquals(uniquesFieldValues, kapuaEntityUniquenessException.getUniquesFieldValues());
+            Assert.assertEquals(KapuaErrorCodes.ENTITY_UNIQUENESS, kapuaEntityUniquenessException.getCode());
+            Assert.assertEquals("Duplicate " + type + " entry for values: " + uniquesFieldValues, kapuaEntityUniquenessException.getMessage());
+            Assert.assertNull("Null expected.", kapuaEntityUniquenessException.getCause());
         }
     }
 }  
diff --git a/service/api/src/test/java/org/eclipse/kapua/KapuaIllegalArgumentExceptionTest.java b/service/api/src/test/java/org/eclipse/kapua/KapuaIllegalArgumentExceptionTest.java
index c09353c5cd2..eed9b85e3a2 100644
--- a/service/api/src/test/java/org/eclipse/kapua/KapuaIllegalArgumentExceptionTest.java
+++ b/service/api/src/test/java/org/eclipse/kapua/KapuaIllegalArgumentExceptionTest.java
@@ -80,7 +80,7 @@ public void kapuaIllegalArgumentExceptionKapuaErrorCodesStringParametersTest() {
                         "Error: " + name + ", " + value,
                         "An entity with the same name " + name + " already exists.",
                         "An entity with the same external Id " + name + " already exists.",
-                        "Error: " + name + ", " + value,
+                        "Duplicate " + name + " entry for values: " + value,
                         "The current subject is not authorized for " + name + ".",
                         "An illegal value was provided for the argument " + name + ": " + value + ".",
                         "An illegal null value was provided for the argument " + name + ".",