unity 5 upgrading errors

Hi everyone i have this problem that i’m stuck in like week now …
i have opened my source code developed by unity 4.6.4 in unity 5.6.6 since the last Facebook SDK required unity 5 … and when it upgrades i get this Error …" unityeditorinternal.internaleditorutility does not contain a definition for addscriptcomponentunchecked( gameobj, script ) "

please if anyone here got an answer … and sorry for my broken english guys

Replace the Create() Method like this. It should Works. I tested this code on Unity 2018.2.8f1

private void Create ()
	CreateScript ();

        //Old Code
        /*if (CanAddComponent ())
			InternalEditorUtility.AddScriptComponentUnchecked (m_GameObjectToAddTo,
				AssetDatabase.LoadAssetAtPath (TargetPath (), typeof (MonoScript)) as MonoScript);*/

        //New Code
        if (CanAddComponent()) {
            // Need to use reflection to access this now (it is internal)
            MethodInfo addScriptMethod = 
                BindingFlags.Static | BindingFlags.NonPublic
                null, new Object[] {
                    typeof(MonoScript)) as MonoScript
        //New Code End here

        Close ();
	GUIUtility.ExitGUI ();