diff --git a/Svelto.Common b/Svelto.Common
index b333fcd..a1f5f55 160000
--- a/Svelto.Common
+++ b/Svelto.Common
@@ -1 +1 @@
-Subproject commit b333fcd47178138a48602493fa21665ca95e1549
+Subproject commit a1f5f55c8b28f66ed033fa02c425dfa16c3c30e6
diff --git a/Svelto.ECS/DataStructures/TypeSafeDictionary.cs b/Svelto.ECS/DataStructures/TypeSafeDictionary.cs
index e659df5..d7100c3 100644
--- a/Svelto.ECS/DataStructures/TypeSafeDictionary.cs
+++ b/Svelto.ECS/DataStructures/TypeSafeDictionary.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using Svelto.DataStructures;
+ using Svelto.DataStructures.Experimental;
  using Svelto.Utilities;
 
 namespace Svelto.ECS.Internal
@@ -135,7 +136,9 @@ namespace Svelto.ECS.Internal
         public uint FindElementIndex(int entityGidEntityId)
         {
             uint findIndex;
-            if (FindIndex(entityGidEntityId, out findIndex) == false) throw new Exception("");
+            if (FindIndex(entityGidEntityId, out findIndex) == false)
+                throw new Exception("Entity not found in this group");
+
             return findIndex;
         }
         
diff --git a/Svelto.ECS/EntityViewsDB.cs b/Svelto.ECS/EntityViewsDB.cs
index c994e43..66268ce 100644
--- a/Svelto.ECS/EntityViewsDB.cs
+++ b/Svelto.ECS/EntityViewsDB.cs
@@ -52,7 +52,7 @@ namespace Svelto.ECS.Internal
             return ((TypeSafeDictionary<T>)typeSafeDictionary).GetFasterValuesBuffer(out count);
         }
 
-        public T[] QueryEntities<T>(EGID entityGID, out uint index) where T : IEntityStruct
+        public T[] QueryEntitiesAndIndex<T>(EGID entityGID, out uint index) where T : IEntityStruct
         {
             TypeSafeDictionary<T> casted;
             if (!FindSafeDictionary(entityGID, out casted))
diff --git a/Svelto.ECS/IEntityViewsDB.cs b/Svelto.ECS/IEntityViewsDB.cs
index 0a3b1cd..8e5bede 100644
--- a/Svelto.ECS/IEntityViewsDB.cs
+++ b/Svelto.ECS/IEntityViewsDB.cs
@@ -33,7 +33,7 @@ namespace Svelto.ECS
         //to use with EntityViews, EntityStructs and EntityViewStructs
         T[] QueryEntities<T>(out int count) where T : IEntityStruct;
         T[] QueryEntities<T>(int group, out int count) where T : IEntityStruct;
-        T[] QueryEntities<T>(EGID entityGID, out uint index) where T : IEntityStruct;
+        T[] QueryEntitiesAndIndex<T>(EGID entityGid, out uint index) where T : IEntityStruct;
 
         //to use with EntityViews, EntityStructs and EntityViewStructs
         void ExecuteOnEntity<T, W>(EGID egid, ref W value, ActionRef<T, W> action) where T : IEntityStruct;