Upgrading errors

[Jefemcownage]

tk2d Undo/Redo callback failed. Undo/Redo not supported in this version of Unity.
UnityEngine.Debug:LogError(Object)
tk2dEditorUtility:.cctor() (at Assets/TK2DROOT/tk2d/Editor/tk2dEditorUtility.cs:18)
UnityEditor.EditorAssemblies:SetLoadedEditorAssemblies(Assembly[])

NullReferenceException: Object reference not set to an instance of an object
tk2dSpriteCollectionBuilder.Rebuild (.tk2dSpriteCollection gen) (at Assets/TK2DROOT/tk2d/Editor/Sprites/tk2dSpriteCollectionBuilder.cs:690)
tk2dSpriteCollectionBuilder.RebuildOutOfDate (System.String[] changedPaths) (at Assets/TK2DROOT/tk2d/Editor/Sprites/tk2dSpriteCollectionBuilder.cs:151)
tk2dSpriteCollectionTextureWatcher.OnPostprocessAllAssets (System.String[] importedAssets, System.String[] deletedAssets, System.String[] movedAssets, System.String[] movedFromAssetPaths) (at Assets/TK2DROOT/tk2d/Editor/Sprites/tk2dSpriteCollectionTextureWatcher.cs:24)


Any ideas?

[unikronsoftware]

You will need to update to 2D Toolkit 2.3. Unity changed the undo system in Unity 4.3